Hey there!
I had the same issue, I'm sure most do when the setup a tent. I found that by removing those dinky wire hangers the lights come with and attached one ratchet clip to each side of the light solved the problem. Having your mounting points as far apart as possible will increase stability. My mounts are close enough to just use the clips from the wire hangers and ratchet ropes so two works great. In your case you'll have to get creative, maybe shorten the wire hangers. Using 4 ratchet ropes would keep it strait, that's for sure.
Hope this helps!🙌