Really nice build.
One thing that kind of jumps out at me is how beefy your chassis is... except for the trailing arm pivot brackets. They look like 1/4 inch thick plate (or so), which is beef, but without any gussets I would keep a close eye on those to make sure that they don't start to fold over or tear out. There will be a lot of twist and possible side loading on them due to the lever arm of the trailing suspension.
I had a similar situation on my boat trailer where the tilting tongue attached at the pivot bolt. There were no gussets and the torque from the offset jack wheel caused those brackets to twist, and the pivot bolt hole to wallow out. I fixed it by adding gussets, an anti-crush sleeve and restoring the bolt holes by welding on thick washers.