ausracer
I don't run caps, but you are basically correct that it works like a sedan tire with an insert. You can true the foams to a camber angle before mounting the caps and you don't have to worry about balooning as much as you would a non-belted tire.
dugrant153
Try
www.mdiracing.com and
www.castlehobbies.com. Both carry parts for the Tamiya and Cross cars. Les at MDI is great at special ordering stuff that you have trouble finding, so email him if you don't find what you are looking for. You might also check
www.ehobbies.com and
www.towerhobbies.com for Tamiya stuff. Once in a while, they have esoteric stuff.