I am currently fixing up my 14' semi v. I also have a 12' semi v on one lake with plywood on the seats and one hatch. It works great in rougher water from pleasure boaters with just a trolling motor. I am looking to fix my 1o' jon boat for another small lake. I want to put a piece of plywood on the front. with a single hatch. Will be using a trolling motor only. Will also reusing a transom wheel to bring it to the water. Any tips?

Yes, but unless you know a guy who can weld aluminum it can get pricey. 

 

Try to find an aluminum welder who will put in some floor joists for you though.  If he welds to the hull reinforcement bands, it will give you a super strong lightweight floor.  Once you have strong joists, light gauge plywood is fine, but you HAVE to put 2lb density two-part foam under that.  It will expand, making your floor super solid, your structure one integrated piece and also makes your hull leak-proof.  Make sure you mind the weight on every single item- and try to remove as much "old & heavy" with "new & light" as you can.  

 

Here is a link to a 12' boat I made.  It's pretty much perfect even after using it a bunch.  Definitely learned a lot during the process!