I just came across this thread and having built literally several hundred trailers over the years, I would suggest that if you decide to do something similar to the trailer @THE FRENCHTOWN FLYER built, you should give thought to priming the inside of the tubes. I'm not saying anything bad about his trailer, as a matter of fact, it's one of the nicer ones I've seen. Most of the side rails on small campers are made with schedule 14 material, and they are not primed inside. There are holes for wiring to run through the tubing, and they are sources for moisture. Rust will occur inside the frame through leaks and condensation. You won't see it until the trailer breaks. Inside priming is a fairly inexpensive thing to do, and it will save you some aggravation one of these days.
The Jalopy Journal
