Re: deck supports
I used 3/4"x3" flats of pine on my 12' aluminum V-hulland tied it down with stainless screws such that the pieces can be lifted out to wash the boat. The sections resemble decking that you'd see attached to a house(my buddy told me to make them close enough together so that cigs/lures/sinkers don't fall thru if dropped).
I built a section for the tiller driver to stand on and also below the transom to distribute the weight of batteries/gas tanks stored aft.
I agree, much nicer standing on flat decking than thin curved aluminum while fishing

They did add more weight to the boat than I anticipated though.
I haven't sealed or varnished the pieces, considering bedliner.