You're making great progress on the camper and it is really starting to shape up!
You'll be camping before you know it.
Those home brew stabilizers are well executed, too, but I hope you are aware that PVC can be brittle at low temperatures, and I would keep an eye on the pin holes. When PVC is point loaded like that (the small area of the pin concentrates the load on what is now a weak spot in the pipe...the hole) it can split.
I like what you have done , I'm just saying that it could be something to look out for depending on your usage.