My adventure started when we headed to san antonio the jayco was in storage and while there a field rat found its way in.... and died.... upon searching for his entrance i discovered the previous owne...
Boaters face this problem all the time. There are products that will infiltrate the rotten wood and make it hard again, epoxy resin hard. Git-Rot is one and West Systems makes another. Google will find directions for you.
I would find ways to add these products to the rotten wood, seal off all ways for water to get in and get on with life. Maybe by drilling 1/4" holes above the problem areas and also below and then add the stuff at the top until it comes out at the bottom.