Looks good, but IMO:
Originally Posted by
Radials983
I would also suggest the truss sides.
+1 - It'd be a lot stronger with something like that.
Another option ...
As you torque down the turnbuckle you would apply a pre-load to the bottom of the trailer. This would make the top want to flex upward, which when loaded will flatten out.
That wouldn't flatten out since the whole thing's supported in the middle, not the ends. Needs preload across the top, bearing down on the axle.