At the long beach show, someone was demonstrating a carousel press that was doing all over prints. The shirts were simply laid on an oversized platen (like a 3ft X 3ft piece of plywood). Sorry I don't know who had it, but know there is an alternative to a belt printer. Hopefully someone else who was there can chime in with the company doing it.
Here is an article on all over printing using transfer. They used multiple 11X17 sized transfers.
Sublimating Hoodies in All the Wrong Places
This may or may not work depending on your design.