I could easily plane (and keep planing - just not very fast) on my vomit in plus 12 knots with a 7.0 and a 34cm fin. It just took pointing off the wind and a "bit" of pumping to get it going!
If you are serious about sailing in the pus, a formula board is the way to go, with a nice big 10.0 or something like that. I tried sailing the pus last winter with a ~125l slalom board, biggest sail was 8.5, it was enough sometimes. A formula set-up would have seen me covered. This winter it is storms and small stuff for me

Lets hope they they are regular