Tom - I moved your post to its own new thread because it was not really related to the problem in the thread where you originally had it. You should get more interest in a thread of its own.
To begin with, I don't think you risk any additional damage by moving the trailer in this condition (with the top down of course). I don't believe it's structural at all - I think it's just cosmetic.
To repair it, I'd try to remove that trim strip with the top on, (possibly lowered just a bit to get it away from the "lip" on the lower half) and maybe remove the inner trim strip on the lower half to gain further access. As you work on it, you'll see how it was attached. It may be glued.
I've replaced an inner trim strip on my HiLo with a length of hardwood I bought at Home Depot that seemed a near perfect match, both for appearance and for width and thickness. I suspect you could do the same here. Again, it may give you better access to work on it with the top partially down.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew