Personally I would go with a double layer of plywood. 3/4 first then put down a coat of epoxy and while it is still wet put a thinner layer of plywood topped with epoxy and finally your Tuff Coat. As far as your batteries and fuel go once you move to a center console I would mount the batteries in from of the console and te fuel behind the console. If you put one on one side and then one on the other side the weight will get out of balance as the fuel is burned. The weight of the battery weight is not going to change. One option would be to mount the batteries in the center and split the fuel tanks so that you have one on each side. Draw out of both at the same time to keep that part of the weight in balance. Just my