As to the "cleaning on the water" question, game wardens are going to use common sense. They are pretty darn good at discerning "intent."
If you are fileting fish on a boat in Opossum Creek, and you're staying at Island Cove .... yea, cleaning fish on the boat would likely be a problem. You are clearly "still afield."
But if you're sitting inside or near the marina fileting fish, with your cabin (or hotel) in sight, and you have clearly wrapped up fishing... rods stowed, nobody sitting there casting, etc., chances are you're OK. You are not really "afield" anymore. A game warden has to be able to convince a judge that your "intent" was to break the law. If you are clearly done being "afield," no problem. Your attitude and demeanor is going to mean just as much as your location.
As to cleaning fish at the boat ramp, I don't have a problem with that. I simply ask that you take the time to haul the leftovers out in the water far from the ramp proper. emoThanks
I also wish some marina(s) would build fish cleaning stations. I frequently have clients ask about this. See <a href=http://www.chattanoogafishingforum.com/forums/thread-view.asp?tid=87814&posts=2&start=1>this thread.</a>