I have the same issue on mine.
I found that they are actually standard nuts, tacked in to the bottom plate. I fished around with a piece of brazing rod, but a coat hanger would work too. Once I got it close, a little coaxing, and I was able to tighten. I used locktite to keep it in place.
I talked to a rep from Reese at the Hershey show to see if I can use a hole saw through the top beam, but he was pretty sure it was double thickness in the area where I would need to drill.
The locktite didn't do much as I need to adjust periodically. To adjust I tighten the bolts slightly, hitch up and I use a part of a shovel handle to gently drive the wedge in place.
I then un hitch and pull forward enough so I can torque the bolts down.
I have only had to do this a few times a year.