bench replacement in 14 ft. jon

I have an old jon boat that has had the front bench seat removed completely, there is now just a row af screws across bottom of boat where the bench was riveted(to plug the holes). My concern is that the bench is supposed to be there for structural reasons and am wondering if anybody has any ideas on what i can do to fix it, if anything. It is an old riveted jon, but I'd like to use it until I can afford something a little nicer. Thanks for any help.