The setup on our Coleman Utah utilized a plate welded to the frame and bumper supports and the receiver. I no longer have it to provide pictures. My F-I-L did the work and wa-a-ay over built so it was rock solid. The Coleman bumper was also more substantial than FR puts on.
As alluded in my post above, it has a LARGE impact on weight distribution since the bikes are a larger percentage of a pup's overall weight vs a TT. Not thinking, I started a long trip with 4 bikes mounted there and had to move 2 onto the front trunk of the Utah in order to balance it. I believe even 2 bikes would have been a problem back there without the two bikes lashed to the front of the trailer to balance it out. After that trip I switched to the pro-rack.
With the rear mounted rack I still had to remove the bikes to set up since the beds did not clear the bikes. I would recommend against putting a bike rack back there.
2016 Roo 21SS, 2016 F150
2015 Rockwood 2514G (pup), 2015 Fd Expl,
2003 Coleman Utah (pup), 2007 Fd Expl