If these are the same Lippert Engineers that designed the trailer frames and leaf spring hangers that I've repaired, I'd like to talk to them as well!
So, where are we with this discussion.....oh yeah......bike racks.
I run a 4-bike rack that I picked up on the road at Wal-Mart when my Yakima rack self destructed., The quality is surprisingly good and it's held up two seasons perfectly. It also folds down to avoid getting "clothe-lined" when walking behind the camper. I bought it for temporary use, but it works good.
http://www.walmart.com/ip/Deluxe-4-Bike-Carrier-for-2-Hitch/10812001
I've seen two of the eight campers in my camping group have bumper failures in the last two seasons. You are at the mercy of the skill of the welder that sticks the bumper tube on the frame. Unfortunatly, not alot of time is spent in this area. Oftentimes from what I've seen, the welder has been set "too hot" and what should be weld is more of a quick burn through with very little filler metal deposited.
Combine this with the crazy dynamic forces at the tail end of your rig + some time and fatique = <FAILURE>
Some get lucky, some get better attention when built.
My last trailer actually looked pretty good, I still built a full receiver hitch. My friends trailer (same brand X) failed with two little girl bikes on one of the first trips.
I would just hate to see some motorcyclist getting hurt by a loose Schwinn sliding and bouncing through traffic.