You haven't given any details about the vintage or construction of your RV. Dry rot is a fungus that can destroy untreated wood in ares of poor ventilation. Often in the front of a Class C cabover, it's actual wet rot from leaking windows or seams. The superstructure could be 1 x 2 fir framing, aluminum, or steel frame under a fiberglass or aluminum skin. No way to tell from what you've said so far. Something has given you indication there's an issue, it won't get better by itself. I'd start by removing bedding, flooring, perhaps interior sidewalls, even ceiling, to get at the 'rot' of the problem. You might have to remove insulation, especially if it's wet or covered in mold. (Use lot's of ventilation and wear proper protection) Lots of online advice on how to treat and remove mold issues, don't shortcut it or you'll just have to do it again. Leaving any wood with rot in it will just spread to other replaced wood over time, remove it all if possible. A product like Git Rot is a type of watered down epoxy resin that can flow into damaged wood and encapsulate infected wood. It's a good product, I've used it over the years in repairing many aged wood boats, but it's not a cure all, just an aide when repairing rot in structure that's sound but has been exposed.
Go slowly, save any wood removed as patterns for replacement lumber. One piece at a time out, one piece at a time in, and it will soon be good as new.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI