I carry 4 bikes on my bolt on receiver on the bumper. I do have the bike rack attached to the back of the trailer wall to eliminate the bounce the back of the trailer initiates. the bounce is what causes the failures! even with a receiver bolted/welded to the frame you still need to eliminate any bounce. I`ve had 4 bikes on the back of my TT for 7 years with no issues. I have a camera and can watch them and they don`t move even over dips in the road. to mount bikes on the rear of a TT/5th wheel you need to know a little bit about physics! you can`t just go out and attach a rack to the rear and head out! it needs to be secure and you have to reload the trailer to compensate for the reduced tongue.