Okay, so I finally got a confirmation that the tubeless conversion WILL work on a stock 18" rear wheel running Dunlop 908's, so I'm going forward (albeit painfully slowly) with this.
I'm ordering 3 of these (one for 18" rear, two the 19/17s):
One question: Should I apply the the silicon OVER or UNDER the valve stem? Or perhaps leave a "hole" in the silicon so the valve stem mount bolt can be against the rim? Maybe it will become clear when I receive the valve stems...
Not sure if anyone is watching this thread, but I'll report back, could be a few weeks. I'm planning on using reg. caulk I guess. Cheap and available if I need to undo/redo (likely!