Thanks for the thoughts. I don't have an axe to grind on this and I agree that a lot of approaches will work fine for most people. Ultimately I think a rolled tire is going to be about an insufficient process, not a bad method.
I know a dude who bought a bike with tubular wheels and tires and rode it on a track a bunch of times before realizing that the tires weren't glued to the rims!
Mark's explanation makes sense to me - a thicker layer allows some fudge room for where the tire and rim don't perfectly meet. But: in order to have that fudge-layer/gap-filler, does the glue still need to be tacky? Does letting one thin layer dry and adding another one harden things too much? And, ultimately, are two thin layers any different than one thick layer?