94 GMC Safari Van Heater Conversion?

We are building a bed in the back for short camping trips. I want to install a very small heater to keep us warm at night. Don't want to use kerosene or disposible propane bottles. I have a 5 gal propane bottle, but don't know what to hook it up to. Also want to do this as cheaply as possible as we will only make a few overnighters this winter. What has worked for you?