I agree with SODO, w/o pictures we are stabbing in the dark on answers/ideas. Sometimes terminology creates a barrier as we all tend to describe things based on a knowledge base that may not include the technical nuances of the situation. Just turning the trailer over as you described in your OP could induce stresses due to twisting. Time to re-evaluate all the things you have or have not done.
Maybe with better info we have a trailer fabrication professional that will weigh-in with your solution. I do not fall into that category.
I made a grievous mistake on the first trailer I bought for hauling my first tractor. Almost lost it at 30 MPH when the homemade trailer started to flex under the new load. Promptly scrapped it as too dangerous to sell to someone else. All the things you are describing are exactly why DOT requires engineered designs and certified welding on DOT rated trailers. The life you save may be your own.
Ron