When its mental (>20knots) And whitewater everywhere, I have a system that usually gets me up on my 7' sup
get out as deep as I can
let a wave hit
jump on and hang on
let a wave hit
get the wing up
let a wave hit - usually heading for the shore a this point pushed by white water
maybe one more hit trying to get some power in the wing
stand up and go

I did have reasonable success on a 50l board once - but It wasn't in crazy windblown.
I had high hopes for a my newly converted 80L board but.... its worse than the short board ! - its too big to sink and too small to kneel on !

Lets have some tips then - getting up on a sinker or a semi sinker.