Well you could try, lol, but good luck. Not sure what a take & bake is, but if my assumption is correct, taking a frozen pizza home to cook is worlds apart from walking into a pizzaria for a slice.
On a personal note, as a taxpayer, no I don't think they should be able to use them at an ice cream truck. If you need assistance, fine, but goto the supermarket and buy a half gallon and be economical about it.