Rotten Wood

As a builder for 35 years I can say treated lumber is junk, lowest grade they can get away with. You will also end up with 1 grade less than a normal stamp if you buy at a box store. Treated is also hard on fasteners. I just replaced a floor in my lund the plywood was ok but all the fasteners rusted away causing failer. J B has a great suggestion if you can find some exotic wood . I wood stick with good grade pine and treat it yourself. Glue and screw everything. Keep the moisture out and you wont have a problem. Easy to say I am facing the same issues myself need more time and space.

I've used redwood and pressure treated wood in the past when replacing framing material. I would think cedar would be great as well. I usually get 2x4's and cut to fit. Doug fir would probably be fine but I always assume it will leak again at some point even though I try my best to prevent that.

Joe, good advice great info. Don't know how many hours I spent rebuilding that entrance door.

When I had to rework the wing and back corner of my previous Lance camper, I was able to purchase all my wood at a marine ship's store near where we live. Both African mahogany and South American sepale woods are claimed to last at least 25 years in a marine enviroment, so those are the woods I used in the rebuild. That and some marine plywood which I encapsulated in epoxy resin.

I wanted my work to last longer than would the rest of the camper. Marine woods tend to be sold in random widths and thicknesses increasing by one quarter inch. Some of the wood, I had the shop where I bought it, run it brought their thickness planer to get the exact thickness I wanted.

The real cost in any of these jobs is the labor, not the materials. What I originally thought was going to be an 8 to 10 hour job, ended up taking me over 80 hours as the rotten wood damage was more extensive than I had thought it was going to be.
Even though I no longer own that TC, I know my repair job will never need to be redone, even if the caulking is allowed to fail.
I probably spent an extra $150 by using marine hardwoods instead of common lumber that I use on most other building projects.

I had to rebuild the door to my pop-up Sunlight and used whatever good pieces of scrap that was in the garage. The problem you will have is fastening the pieces together. The manufacturer used large staples to allow the joined pieces to flex when the unit was under torque stress form rough roads that twisted the cargo box. My door had sagged and was rubbing the sill. I used 2x2 steel angels at the corners to maintain 90 degree angles. If weight is not a problem you might consider using larger pieces for greater strength.

pine is fine if you keep up maintance of caulking.. my camper was rebuilt using regular lumber..if your worried paint the wood before reskinnng

When I re-built the front end of my TC I was able to find 2x2 cedar for free on Craigslist from someone who was building their deck. Cedar is good because it helps with mold issues. It's not to soft and it's not to hard. Then I painted it with an exteriour house paint to also help give it another layer of protection.

Josh

Nothing bad about using wood to compliment the remaining wood. Pressure treated OK if you can find sizes. Most likely no. Could cut up pressurized 2x4 or 2x8 to size. My opinion oak is unnecessary. Douglas Fir is OK with no knots. Red wood is good too but soft. Depends on the application.