Hi mate
Yeh I agree ventilation is more common especially in alloy boats because of large keels,chines ect causing air bubbles not like fiberglass where the bottom of the boat is more smooth
U could go up a prop size or have cup put in ur prop it would help and bring ur rpm down a bit saving a bit of fuel and engine wear but it wouldn't pull a ski/ tube out of the water as well.
A permatrim will help get on the plain but I don't think it will fix ur ventilation
I had cup put in my prop it stopped the ventilation and lowered my rpm by 350 rpm it just allows the prop to hold the water better.
It's well worth checking those transom mounted things u will be surprised how something small can effect the problem