Depends on what your definition of "Big Ole Smoker" is. If you are talking about something the size of a Lang 84 then you would be just fine. if you are speaking of one of those monsters that Klose or Gatorpits makes that has everything under the sun on them them you make want to make sure you have something like a 2500 Chevy or F250 or larger but something like a Lang 84 will tow fine behind a Jeep or Toyota, I'd recommend maybe equipping the smoker with a trailer brake though.
Now that we have addressed what can tow a smoker you have to consider all the other things that get brought along for a barbecue if you are towing it somewhere like coolers full of beer, ice, meat, etc. Plus everything else for a days event of fun barbecuing. I usually ended up with a long bed truck full by the time I was ready to leave the house. If you are thinking about a business (being as you posted this in the catering forum) forget the smaller vehicles. When I head out to large events like weddings I have a E350, a full size Chevy truck and 6 x 12 enclosed trailer along with a mobile catering trailer and still could use more room. Just recently added a Honda Odyssey to bring our staff along.
