When we were in Perrot State Park in Wisconsin a couple of weeks ago, we ran into a couple who are avid (understatement) outdoor folks. They had a 2008 Roadtrek C190P and were carrying hiking gear, two full size bikes, and two small (non folding) kayaks. They had built a pretty clever rack on the back that carried the two bikes and the kayaks, all vertically.
I did get some pix, but they had already unloaded the kayaks, and we were heading out, but they were on the passenger side of the rack, vertical, with the open part of the kayaks facing each other.
The bike weight hangs off brackets on the handlebars on top, and the tire pushes on the spare tire cover,
The Kayaks go on the standard Kayak holders and are strapped against them. The kayaks are taller at the ends, so they can't slide down.
It does swing away on a pivot on the passenger side, which I couldn't really see because of the boxes. It must not be very strong against droop when not pinned on the other end, as he added a tongue type support to hold it up when swung out, and interesting idea, as the pivots are hard to get durable without making them bigtime heavy.
It is made of steel tubing, and he said it weight about 100#. With a couple of bikes, the kayaks, and boxes, I would guess he would be a bit over 200# total, maybe with the center of gravity about 10-12" behind the hitch. They said they didn't notice a change in handling with it on.
They may remake it out of aluminum to lighted it up bit. Some built in pads and supports would be on my list to do, also, but it is one of the best carriers for this very awkward stuff that I have seen.
First time using the pix hosted on here, works pretty nice, Marco.