Good points, all of them. I looked into the length of a 125 (Chinese knockoff) and it is 72" in length with the wheels on. I too had thought about taking the front wheels off. With the front wheels on, however, it is as you say. I might get ONE in the box, but no way will both go in there. We have an 8' box on this 06 GMC, but it is no way wide enough. I put three bicycles in there, and still have room for wood and some other tall items and still leave room for trailer clearance. The pin box on the trailer protrudes beyond the length of the trailer itself, and I mount the hitch in the rear mounting holes (about 6" behind the axle) as the trailer only weighs 4500#.
I had also though about building a rack that sits on the rails of the box behind the cab but ahead of the trailer, allowing both bikes to sit fully crosswise between cab and trailer. This might be more work than I am willing to go to however, as well as the issues of getting them up and down from there.
Thanks for the suggestions.