We have a 2019 Open Range 2504. I suspect we have the same lippert frame as you. The frame spring mounts have a brace welded on the inside of them for some support, but we bent an axel (2 3/8" diameter) going over some dips in the road a few years back. bowed the wheels completely outward. I had the axles and springs replaced by a local suspension place (
Standens) with 3" tubes and they installed new springs as well. Those 5" long shackles have so much leverage side to side they can still tear welds in tight turns. I installed an x-brace across the center mount. Necessary? Who knows, but after the bent axle, I tried to strengthen the frame where I could. Relatively simple installation if you can lift the trailer. Everything bolts up and added a wet bolt kit and
equa-flex center pivots as well.
The real problem is that the trailer has a 7400lb GVWR (load range D 205/75R15 tires though) and the axles, combined, have a rating of 7000lbs. Way too close to the limits even if tongue weight is 800lbs or so. A 7500lbs trailer should have axles that are rated, at a minimum, for the full weight of the trailer.