Mount 100lb mini-split condenser to rear wall?

I built my hitch for bikes so I used 2 x 4 x 1/8 tubing... the iron yard had the remnant already cut. The hitch is all welded but I bolted the completed hitch to the 5er frame so I didn't have to weld next to all the flammable materials. It won't go anywhere with 6 - 5/8" bolts going through the 2 x 2 x 1/4" tubes that then go into the heavy backing I put inside the frame tubes.