All sounds like solid logic. Just asked my mate how many bolts hold his 115Etec on and he only has 4. No problems with that as far as I know
but KWIL is the man to ask. Six bolts aside....raising or lowering was pretty easy. Just supported the skeg on some blocks of wood, removed the 2 hole'd bolts, loosend the 2 slot bolts enough to allow the engine to slide and used the trailer jockey wheel to raise or lower the front of the boat /trailer to get the right height. Pushed the bolts back though with a squirt of sealant and tightend it all back up again.
My cav plate runs just breaking the surface which produces a lot of spray. I think that I could do with a half hole higher but as I am not willing to drill more holes in the transom
it will have to do. Even if it was a perfect set up I don't think I'd be able to squeeze another 8 / 10 kts out of it.