Don't mind me, just imagining a Vigcup proposal while I eat breakfast
Like Viggo finding out from Hiccup about the song Stoick sings with Valka (The Dancing And The Dreaming) then promptly going to ask Stoick permission to use it
Only he never asks permission for anything usually, so he makes a big prepared speech on why Stoick should let him, how he's family whether the man likes it or not so he should let him propose.
Then, as he starts on the second half of the speech, Stoick cuts him off.
"Alright. You can propose to Hiccup so long as you stop blabberin on."
It leaves Viggo dumbfounded. He was expecting more pushback. They have a heart to heart, their first and probably only one. It ends with Stoick threatening Viggo if he ever hurts Hiccup and Viggo laughing with Stoick after.
Then, the proposal would be in the cove. And of course Hiccup says yes.