I suggest you try Papilio in Texas - Clear Laser Water Slide Decal Paper. As well as the standard thickness in clear and white with laser or inkjet versions they also produce a thinner carrier waterslide paper.
I buy my transfer paper from the Crafty Computer Paper Company it says the site is down at the mo though. I haven't used it for boiler bands but a great many other things with my laser printer. It forms well over I regular surfaces using the normal Micro sol - Micro set solutions. Link below
Mark J