Need fiberglass pontoon rebuild advice

[captkirby]

Inherited a 22' 1989 adventure fiberglass pontoon boat.
The 26" pontoons are in great shape. the deck along with 2-4 aluminum cross members need to be replaced and the vessel needs repower.
My theroy is to remove all the cross members and simply glass 3/4 ply,with roven and mat to the pontoons. I would like to do this so i can utilize the space in the pontoons for batt, fuel and storage compartments,and make it water tight getting rid of all alum so i don"t have to worry about future corrosion problems.
I figure to install compartments in the hulls i would install bulkheads 5 feet or so, and foam in all unused space for positive floatation.
Then have watertight deck hatches to protect against seas and weather.
I am planning to make this vessel into a center console with t-top,leaning post and above deck bait well. I want to keep it extreamly simple and uncluttered for fishing.
So what i would like advice on is basicly, can i glass the deck to the pontoons without cross members? And what would be a good horse power to run the vessel around 30 knts?

I used to have a 20ft aluminum pontoon that worked good, but its was to cluttered,and eventualy the salt overtook the alum. and at that point its hard to fix corroded alum pontoons. At least with this i figure no corrosion and i can fix it.