I am more use to replace roten logs on a cabin but I think it is simular, any pirce of wood that is
Roten I would replace the entire piece if possible or as much as it is possible,
Some time you can also fix a portion with a kind of plastic wood specialy if it is not a suporting
Piece, I would use very dry wood like pine and use glue at the joints, their are very good wood
Sealant , look under log home repair on the web you will find good suggestion, as far as outside
Sealant 3m has very good products and also all campers store have special sealants,
If you check on this site you will se that some people completely rebuilt a camper, their is no reason you could not do it, good luck
Gaetan
Gaetan St-Hilaire
2004 silverado 4/4 2500HD long box Duramax/Allison
2003 everest 323k
2003 northernlite ten 2000 rd