gerry johnson If you are going with a insulated container I’d go with electric. I just used a turkey fryer burner from amazon but my smoker is open. I wouldn’t put gas into a sealed container. You’ll also need to put a in and out for air flow. I’d bet that you’d be able to use a single electric hot plate, they even have doubles on amazon, pretty cheap–$10-$15 for a single. that way you could put sawdust in one and water in another. If it seals you’ll be suprised how much heat it will hold so you won’t need a lot of heat from a propane burner, probably overkill.
If you do get a propane make sure you get a controller with a needle valve, it really allows for fine tuning of the fire. But I’d recommend starting with electric and get some wood sawdust from Waltons. I really like mixing the alder with hickory.