I've repaired more then one rig, if I was buying a rig, I would not
buy one that I knew had rot. My time is worth more then that.

That being said, maybe. I have done it that way before. It's kinda the
reverse of how rigs are built (from the inside out). If you take the
outside off, plus the side, there is nothing to offer any support

I've been there -- and I would avoid a situation with rot.

In my case, I found that the ceiling was sagging and still moist. So I
ripped it all out. Then I found that the beams were mostly rotted. So,
wiht the help of a knowledgable friend I removed these beams and we
put in new ones. Then came insulation of the roof with Roxul Plus, a
vapor barrier of plastic and new panelling for the ceiling. Some time
later, one of the roof seams started to leak, so i had an RV repair
center remove the roof entirely; he found that the stringers running
the length were rotted, so he changed them and then fitted a one-piece
aluminum roof. It turned out quite good. However, once there is rot
somewhere in the rig, there is bound to be more after you fix it. The
rig I had was a 1978 Shasta.

I pledged never to buy a wood-framed RV again. My wife is very
allergic to mould, and once there is rot, the spores are all over the
place.

I should add that after we had had a leak around the chimney of our
hose, the guys that repaired it ripped out all the rot and then
sprayed it with some kind of disinfectant to kill any spores. That
worked quite well.

Frankly, though, if you factor in the cost of labor, it's not worth it
for an older RV.

Howard