I looked around myself for an alternative answer to keeping my prep foods cooled, and I have yet to discover one. As was said already, better to go with a prep station as discussed. I am buying one from webstaurantstore . com for $899.00, its a hit in the pocketbook, but food safety is the most important item on the menu.
Honestly, that sandwich table is going to be one of the best investments you can make. I wish I had room in my trailer for one. It would make my day 100% easier and allow me to do some different things.