Bit late to this (just flicking through), but there is some blog out there from someone in NY who put some Marathons on ghetto-style, and they seem to hold. I hope so, as mine's going to have folding (ghetto)-tubeless Kojaks on Velocity A23 (legit tubeless) rims.
I'm still waiting for the day when someone makes a 16" tubeless tyre. Preferably tan wall, but I'm not fussy.