I’m in a similar situation. 1/2” plywood decking, two 27 series batteries(placed in front of middle bench), 3 gallon fuel tank, tackle and other crap, Lowe 1467UV, 2013 Tohatsu 9.8hp, 4 stroke carb. 17mph gps.
Engine was 3-4” under keel, I raised it, actually put it a little above keel, speed dropped. 13-16MPH, depending on trim setting.
Moved batteries to the stern, struggling on hole shot. Gonna move one battery forward.
If that doesn’t help, different propeller.
My manual has pictures about cavitation plate placement.