With a couple of eye bolts,some cable,turnbuckle and a small piece of tubing,you can build a lightweight truss for the sides of the trailer,no welding.That will keep it from bending.
Yea , works for suspension bridges..
I just got a Book shelf made .. shelves supported by 2 ladder uprights,
braced against each other with cables [stainless long line leader from the dumpster,
tossed by one of the many Commercial Fishers around here]
crimp tubes to make the loops, and turnbuckles ..