Doug and I have been playing around with numerous prototypes of a suction cup equipped kayak car-topping system, something we'd been inspired to do ever since looking at Scott Lovig's Rhino flavoured version. Every prototype we made worked, but each new version better than the next.
Our aim was always to keep it simple, inexpensive and capable of loading something as heavy and cumbersome as a Hobie Tandem Island. Eventually we arrived at a basic bullhorn shape bar fixed with heavy duty RAM suction cups, which are used to mount the bullhorn bar to the rear of a vehicle.
We'd experimented with bars with rollers, clothed or padded bars as well but finally decided to just use a simple PVC pipe, fed onto an aluminium tube pre-bent into shape using a pipe bender. The PVC surface is slippery enough to allow a kayak hull to glide straight on, although one could easily attach a carpeted covering if they felt the need.