What was bill up to during soos and a real girl?
That's a good question! I just rewatched the episode and got a bit inspired.
Most of Bill's conflict in this episode would center around feeling obsolete. That the way Stan views Goldie may one day happen to him if he doesn't have any "worth". It's a bit of a precursor to the complicated feelings he has after Ford returns and begins to be alienated from his family. From Stan.
Here's what I envision happening:
-It starts off with Abuelita consulting Mr. Mystique, aka confiding in Bill about her fears that Soos won't find a girl to bring to Reggie's engagement party. Or to share his life with. Her grandson has never been on a date before. She's worried for him and his happiness. Bill, for some reason, is completely unbothered.
Bill: Soosie doesn't need to find love, love will find him when he least expects it! He'll just be riding on the train of life, minding his business and BOOM! There she is! Besides, no protégé of mine is gonna make a fool outta themselves searching for romance...though Soos is pretty gullible when it comes to scams and feelings...
Abuelita: Can't you do something for him?
Bill: Mrs. Ramirez, you KNOW what my go-to methods are for wooing my lover, and they ain't gonna work if Soos uses them on his prospective girlfriends.
-Back at the Shack! Bill has never liked Goldie. He claims that it's tacky and lackluster, but really it's because he's reminded of another hillbilly in town. So, he agrees with Wendy when she says it's time to throw it out, especially once he has to help Stan free his arm from its metal maw and the oil ruins his pants.
Bill: THAT'S IT, YOU JUST EARNED YOURSELF A ONE-WAY TICKET TO THE BOTTOMLESS PIT, PROSPECTOR!
Stan: No, that's a waste! Let's check out the pawn shop at the mall and see if we can get anything for him.
Bill:...Stanley, no one is gonna waste their hard-earned dough on that scrap metal.
-He does notice Soos flirting with a girl from inside the coat hangers, and then as she screams and runs away, she rips off his eye patch in her hysteria.
Bill: HEY, YOU GOTTA PAY FOR PERSONALIZED MERCHANDISE, LADY!!!
-Soos immediately goes to Bill first, begging for advice.
Soos: "You gotta help me, Mr. Birch! You're the ultimate expert on fate and the inner-workings of the universe! Plus, you have to most beautiful marriage in existence. Please, bestow your mystical wisdom on me!"
Bill: Hahahaha, yeah, that's me all right! Totally don't wing it or anything...But first get rid of this. *rips off the "Out of Order" sign* If you wanna be a winner, you gotta THINK like a winner, not a mopey loser!
-After Stan says to get rich or lie about getting rich, Bill butts in that it's all about selling yourself as someone they need in their life. Then if they need you, love will usually come afterwards.
Bill: It's all about getting your foot in the door!
Mabel: What?! That's not romantic at all! It's so manufactured!
Bill: So are all your favorite rom-coms.
Mabel: Then what about you and Grunkle Stan?!
Bill:...Like I said, Mabel-leaf. We needed each other first. Sometimes you just gotta stick with someone, and it works out alright.
-Later, as they go to bed, Stan says that it's probably for the best to get rid of Goldie. They need to upgrade and get rid of the useless, ugly, old crap that doesn't rake in the big bucks.
Stan: All I'm sayin' is that I should be the oldest thing in this Shack!
Bill: *twirls a white strand of hair in thought*...I should dye my hair soon, shouldn't I?
Stan" Huh? Oh, uh, sure. It's been a while. *plucks at the strand Bill is fiddling with* You're gonna look like a sheep at this rate, ha!
-At the mall, Soos wants Bill to stay for moral support, but Bill insists that this isn't something that Soos needs him for. Stretch your wings like a baby bird and jump of the branch for the first time. Life or death will push you to fly!
Stan: You have too much faith in him.
Bill: I put just enough faith in him! Soos has other worries, like growing un-patchy facial hair and developing a wardrobe that's more than just one dress shirt, a FCLORPing costume, and his work uniform. Besides, everyone needs a little dating trauma in order to properly develop! It's healthy! Just look at me and you!
-The pawn shop said they would have to pay THEM to take Goldie, so Stan and Bill decide to cut their loses and illegally shove the statue in the trash. And as Goldie reflects Bill's image back at him off of the dull, reflective surface, and Bill feels far older than 50-something years old.
-That's when they find out about Willy Badger. Both take offense when Gary says that animatronics is "a young man's game". Bill scoffs and says he could make a robot even MORE entertaining that would blow this big skunk out of the water. Maybe a golden rabbit?
-The next day, Bill is getting annoyed at Stan for being so obsessed with this badger.
Bill: Gimmee like a month to steal the parts, and I'll create an entire clan of rock star badgers for you! You can take them on tour and abuse them to your heart's content since they don't have human rights!!
Stan: Nuh-uh. I will kneel over if I don't have that critter's cash in my hands tonight.
-Bill also does notice that Soos isn't here, and that greatly unsettles him. Frankly, it's unnatural that his so- loyal employee- has broken his perfect attendance record. He eyes the kids suspiciously when they exchange worried glances and tells them they better fix it or else they're picking up Soos' shifts in the future.
-Bill doesn't want to go steal the badger, which Stan finds odd as they pack for the heist. Wendy eyes him knowingly from the cash register, so he avoids her gaze best he can as he gets into his black jumpsuit. At least he'll get into costume for this.
Stan: But you love petty burglary!
Bill: Not for what we're stealing.
Stan: Look Bill, if we wanna keep playing this game called life, we gotta get with the times, and that badger is our future!
Bill: So anyone that you deem old and worthless, you're just gonna get rid of them if they don't serve you any purpose?
Stan: You're actin' like that ain't just how business is. Now- *falls out of window with a pained groan*
Bill: *slightly smirking* ...Wendy, get his orthopedic back pillow.
Stan: *strangled* Thank you
-They sneak backstage, but while Stan is prioritizing snatching Willy Badger, Bill, bored, decides to check out the kiddy stage show...until it gets highjacked by a scorned, videogame ex-girlfriend. He runs back to Stan to warn him that the robots are now on a murderous rampage, but it's too late. As Stan gets punched in the face, Bill jumps on the badger's back and pulls at his ears, but gets grabbed and thrown at Stan who catches him.
Stan immediately goes to protect Bill from the steel punches and gets into a fist fight. Bill tries whacking the robot over the head with miscellaneous items from the arcade, like a table, a mini-gold club, a plastic basketball, but no dice. But it's Goldie who saves the day, biting Willy's hand before it got the final blow on Stan. Bill takes the opportunity to open its back panel to disarm it just as the power goes out.
-When Abuelita comes out of the ball pit, she remarks that she should have never questioned Bill's fortune.
-As Stan hugs Goldie and calls it an "old, beautiful monster" as praises, Bill gets all huffy. Only HE can be called that by Stan!! ESPECIALLY when Stan says all three of them are going to Vegas. That's THEIR town!!
-The Vegas montage shows Stan obliviously happy but Bill and Goldie are beefing in every photo, like Bill glaring at the copper animatronic in the hot tub as Stan sips from a flute of champagne. He eventually prevails in this battle by pushing Goldie off during the helicopter ride. The last photo is of Stan and Bill kissing at the Wed and Breakfast before security finds them and kicks them out.
-The episode ends with them riding in the Stan mobile, the aged car sputtering and making weird noises.
Stan: Poor girl. She's been through it, but she's still runnin' smooth.
Bill: So, you do like old has-beens, don't cha?
Stan: *smiling over at Bill* Guess so, and you're my number one has-been.
Bill: HA! Stanley, baby, we're timeless.
Hope that answers your ask!! I think I went a bit overboard, but these types of questions are fun to me.