I think I would try to talk to the manufacturer. These things are usually just toaster wire in a submerged element and the effect of a lower voltage is just lower heat output. Performance would be the main problem. It might not recover from successive loads of frozen fries as fast as it is supposed to. Of course in a high volume operation that might be a show stopper. Have they looked to see if there is a 208v element?
That would probably be cheaper than a transformer.
