We have a 2013 36RE. We talked to a couple of Lippert engineers at the rally. They said they could weld a hitch to the frame that would not void the frame warranty. The big problem with that is they want $1500 to do it. I think we are going to great a Thule system to go on the cab of the truck. Los cheaper. One thing to consider when putting bikes on the back of a long rig like ours is what the engineers called road harmonics. Two bikes would put a lot of stress on a hitch at the back of the 5er. I didn't like the sound of that (having dealt with extreme vibration environments as part of a job I had years ago), so that is why we will go with the truck can top carrier solution.
Hope this helps.
Mike & Nena Strong
2013 Cedar Creek 36RE
2012 Chevy Silverado Crew Cab 3500HD Diesel 4WD
Nights camped '13: 56 '14: 51 '15: 134 '16: 149