Bottom of my BR slide rotting. What do I do?

These are pics of the bottom of my bedroom slide. The edges of the bottom extend below the aluminum strip and I guess instead of the water running off the aluminum strip to the ground, it hits this piece of material (doesn't really look like wood on the edge) and has run underneath enough that it is damaging the bottom of the slide. You can see where some metal pieces are now exposed and I can actually tell the wood bottom near them has been damaged. It only seems to have affected the outer half of the slide and does not feel soft or unsafe. The other slides also are made this same way but don't appear to quite go as far below the aluminum rail and the bottoms of those haven't been affected and I'm waiting on suggestions for what to do to them so they don't get this way.

I cleaned the edge of this one and put some caulk all across the edge, thus creating a point for the water to drip off instead of running under, if the caulk stays. I don't know if I could put an additional strip of something across the bottom instead of the caulk since it might affect the slides ability to move in and out. Maybe a piece of rubber might work but I'd have to start if kind of high to ensure it would be screwed into solid material. I don't want to go screwing into the sides of the camper if I don't have to. God knows this is going to be expensive if I have to have the slide removed and repaired. I don't think this is coming from the top of the slide or anywhere else as I can't see any other problems on the inside or outside, but I haven't pulled the carpet up on the slide. What do y'all think I need to do, short of a big, carry it somewhere repair bill? https://www.facebook.com/photo.php?fbid=1290499060965081&set=pcb.1290499147631739&type=3 https://www.facebook.com/photo.php?fbid=1290499104298410&set=pcb.1290499147631739&type=3 https://www.facebook.com/photo.php?fbid=1290499134298407&set=pcb.1290499147631739&type=3