Just been to A Guzzi Daytona meeting, two people had self adapted wheels, one had wheels from a Bandit, with selfmade cushdrive, the other had wheels I never heard of, he told that they were light. No pictures, camera forgotten :-(
I found them, TSW3 from http://www.lightcon.de Ask dynotec.de if you are serious, the advertized prize is as high as PVM.