About to fab a transom riser and have questions with cavitation plate

I'm going to be using my little 10ft alumacraft alot this year in shallow rivers and as it stands the 4hp merc I have sits pretty deep. I have a design currently ready to fab that will set the cavitation plate 1/2" under the hull. I'm wondering however if given it's a 10ft with my 200lb butt in the back plus gear if I can raise it higher. from it's actual waterline I could go up about 5 more inches and still have plenty of water around it, but I'm wondering how much this would effect it when running. Especially since with a handle extension and me sitting in the front of the little thing I can actually get it to plane off. So is there likely wiggle room, or stick with what I have?

My limited experience with small motors and aluminum boats has always been what you have described. Cav plate can't be above the bottom of the boat when running. You might get away with it, my concern would be water pickups being under water when under way.