Utility Trailer to Kayak Trailer

I bought a 5x10 utility trailer to convert to a kayak trailer. I mounted unistrut on the bottom layer and then ran more unistrut up for a top layer. The bottom seems fine, but the top layer sways forward and back. I was wondering what would be a good way to stop this sway.

Obviously you need either some angled sway braces, or something like a plywood panel attached to the upright members to stop the sway–both forward and back and side to side.

Run a diagonal piece on each side or
Use strapping or even a 2x4

Ratchet Straps
I made a rack out of threaded pipe and had a problem with swaying. I added ratchet straps to the front & back and that helped a lot. Email me and I will send you some pictures.