I didn't pursue.
I considered doing what SEToyota offered, but didn't want to get in a situation where it was so tight getting in, it might rust permanently in place and become non-removeable without destruction. Hypothetical, of course, but I can envision it. It would take a heck of a squeeze to get it in there, but if he did it before, it can be done again.
I considered cutting the rails to three sided in lieu of semi 4 sided, where they would squeeze in easily, or even drop in. But that would weaken them and I couldn't envision what would happen with side gusts when going down the road with cover on.
I about decided to tear down this like new trailer for possible use as a bobber project. The bed is perfect and to good to scrap, and I offered the trailer for $495 with new tires, rims, brakes, air lines, paint and everything and no takers, so looks like I got to use the parts. I don't want a M105 without a secure cover.
If you only have one or two holes, it should not be the magnitude of the problem I was faced with. VSE makes these trailers BETTER than new, so it's a shame they screwed this one aspect of it up, making putting on easily removeable side rails and a cover all but impossible.