Fixing LEAKS on 5th Wheeler

[tinkering]

Hi,
We were given a fixer upper 1990 ish (will enter the exact info a little later) Sprint Lite 5th wheeler. Some of the vinyl covered wall paneling is rotting inside so the first thing is obvious to me, Fix The Leaks
What is the best and most cost effective sealer to use on the roof, vents, walls, windows, and door frame? We are in Alberta so if somebody knows where to purchase the materials at a decent price in Calgary, that would be helpful too. I see some Eternabond products on amazon.ca but the prices seem high.
I'll post pics later too.

[tinkering]

I am apprehensive about the frame for sure. I will be peeling suspect soft areas back, either from the inside or outside, for inspection and replacement if feasible. Living in Canada's winters slows the rot down on some things.

It will be awhile before I post any pictures but I will remember to shoot a bunch while I proceed.

The roof is aluminum sheet, so I hope the skeleton is intact. I want to seal it all up first and then hopefully proceed with the repairs from the inside mostly. Panelling will need replacement. I will replace any buggered fiber insulation with rigid SM or spray where possible.

Doing all the work myself will keep it viable, whereas hiring it out would render it moot.

I like rescuing things from an otherwise grave future🐶