My brother inlaw recently bought a propane cart made by Custom sales; but when he was thinking this business he talked with a guy in Kansas that was operating a stadium style cart in a mall in Wichita area.
The cart was electric and also had electric grills. I dont know what kind of burners that he had. You would need a commerical style electric source to boil your hot dog water. The electric roaster would work in a pinch they dont cost very much and can be bought at Walmart. I dont know durable it would be for day to day use. An electric griddle is also an option but will cost much more than a roaster.