I found the leak!!! Water comes down the front of the RV, next to and over the front bunkend, over the diamond plate, where the diamond plate meets the floor in front of the hatch. The wood floor is practically visible. Water must have been saturating wood for years. The membrane on the under belly used to protect the wood actually trapped the moisture in. Rotted the wood to paper-thin flakes. have the front partially torn up down to that membrane.
Would it be smart to cover the membrane with some sort of aluminum sheeting? the front part will get coated with boat epoxy and I will install a 2x3 or 2x4 wood frame for a subfloor, then either use traffic master or pergo. fortunately wood under the slide is ok.