I've got a 5HP 2 stroke Tohatsu and a 10' wood-floored inflatable. It'll plane as long as you have less that 300 lbs aboard.
Frankly, I wish I had a smaller roll-up dinghy and a smaller motor. For me, at least, planing isn't important, and I'd prefer the reduced storage space, setup, and lifting.
I guess I'd think twice before seeing planing as a requirement.
Anybody want to trade?
1987 CS 36 Merlin "Kyrie"
"They drove a dump truck full of money up to my house. I'm not made of stone!" -Krusty the Clown