Another option might be a commercial mover. A bit overkill for a few stores, and will knacker the economics of it all, but it would prove the concept before spending any capital. Are there really no smallholders or horse owners near you who might be able to lend or hire something suitable? Our wee trailer has been lent to four people on here already.
Another angle is that we bought a 7 ft livestock trailer, but also got high mesh sides for it. I end up using it most weeks for something or other, even though I've only needed the sheep setup on it for myself half a dozen times now. You might find that you can justify the purchase of a livestock trailer given other use that you'll put the trailer to?