As long as you don't strip the threads on installation I think self drilling tek screws should hold fine. With two of them on the d-ring style anchor points, they'll mostly be loaded in shear, not direct tension. The bedsides are 16 gauge, which is pretty stout already. I used them in my trailer and had a 600 lb machine tool and a 200 lb air compressor strapped down for a trip up the Alcan, and they survived just fine. I don't even know what they were screwed into behind the paneling on the trailer, but as long as I hit a support structure they held just fine. The first one I installed missed and was just into the plywood floor, so I relocated that one.
Yeah, if you used chain and chain binders, you could probably pull them out.
