DH here:
@thewhitehat, I did put a couple of holes on each end, to fix the chain issue from wrapping on itself when I screwed the cap in, instead of a self tapping screw on the chain I used a bolt with some washers and a locking nut on the inside. It now rotates completely without adding additional length to the chain. When I did this I made a new hole dead center in the cap (these had a little ridge on them so had to grind it off to get the hole started) - with that done I drilled out the hole that was for the self-tapping screw (it was slightly off center before because I didn't want to mess with that ridge) and just let it be. There are multiple holes drilled in the bottom and top of the pipe over the entire length for ventilation.
@partsman01: thought of mounting to the other side of the bracket, but back problems and being right handed made it easier to mount the way I did without having to crawl under the trailer so much. Matter of personal choice I guess, rivets may look a little ugly, but its functional.
Status Update: Took the trailer out on its first trip after the mod over 4th of July, bumpy gravelly roads, potholes, mountain roads, etc. It didn't budge. I did make an additional adjustment also, put a velcro strap on each end of the pipe so if there is vibration, the caps won't open spilling my hoses out on the road.