I looked through a lot of builds on this site as reference for many ideas, but none to specific. Adv4x4 on Youtube is probably the best resource i've found for using ACM.
I have not yet finished the exterior corners, but plan on using some angle aluminum. I am waiting for warmer weather for better drying conditions for paints and adhesives. I've attached a image of the test fit of aluminum angle notched to fit around the tent platform. I'll update the thread with better pictures once I complete this.
The doors fit between 1 1/4 steel tube that supports the tent. I welded some 2" flat behind the 1 1/4 tubing and some 3/4" flat on the tops and bottoms to create a 3/4" door jam around the whole door. To seal it I got some Trim-lok from
Amazon. The Trim-Lok is intended to have rounded corners, but for space constraints I plan on cutting them at a 45* angle for mitered ends. I have not yet installed the trimlok as I need to do some touch up on the paint on the door jams. I'll update the thread once the trimlok is installed and will test to see how well it keeps water out with the mitered corners.
The floor is ACM, but I am currently building a frame out of aluminum extrusions that will secure the fridge / sink slide, batteries, water tank, rear drawer and a platform, so the ACM is mostly to keep dirt and water out. I have used the trailer on two short trips without the aluminum extrusion frame and the ACM floor seemed to be fine with some heavy camping gear, but I don't know how well it would hold up to cargo bouncing around and would probably opt for something else if I planned on using it that way.