If youre going to use lin-x or rhino, or whatever, be sure that your wood is good and dry, and I would either fiberglass or epoxy the bottom of the sheet to seal moisture from the sheeting. I mean, depending on what kind of boat you have. Do it once, do it right! Last thing you want is to trap moisture, or have it be exposed from the bottom if there will be ANY sitting water in the hull, or all you work top side will be for none. Dont bother with marine ply, its too darn spensive. Good kiln dried exterior should do the trick, and with the lack of rain for months, you should be able to find some nice dry stuff 🙂
Also, make sure that any fasteners that go into the ply are coated in 3M 5200 or 4200 sealant. You wanna keep the bugger sealed right up, so you dont have to do it again in a few years. Check out the forum at iboats.com for further ideas.
Stu