Air Conditioning Ideas

Hey all, I work on my buddy's food truck and we're trying to figure out how to get it cooler in here for the summer. He's pretty determined to get some sort of A/C unit. We have one swamp cooler but it's not reaching the other end of the truck. We also have a stove, rice cooker, and steam table putting out heat. It's over 100° here in NorCal. Anyone have any insight?