OK I am going to try to save you some grief here! If they will let you, remove the bunch of screws that hold that cover down, and see what the structure looks like underneath. The cover itself is only 1/2 in thick plywood but they did put in 4 cross pieces to support the tank cover. My old one was springy, but the new one is rock solid. I did install a much stronger mounting system than FW had in there as OE.
The issue is that sometimes the structure that the cross pieces is mounted to (firring strips attached to the stringers) can be rotted. I'd want to get a look at that area if possible. The other areas that are prone to rot is anywhwere a screw went thru the floor such as seat mounts. Boat sounds good though.
If you want to see pix of what mine looks like before it was all put back together, go over to :
http://www.iboats.comgo into the restoration forum do a search under my user name Lou C and you will find some pics of what it looks like, or if you pm me an e-mail I can send you some. If the stringers are good, then at most you might eventually want to replace the support strips and maybe the cover too, it's not a bad job to do just that.