a trailer smoker would be pretty easy. Just need some of those big barrels (they couldn't have stored anything toxic) and some 4x2 .120 wall. Actually it would be a pretty easy task now that I think about it. The cost would be around $400 for parts on the high side. I can get the ball coupler, axle, tires, springs, and lights for $150, plus steel cost and your in business.

I would build it as a horizontal line of barrells, probably 2 on each side accessable from each side... one side being a big grill , could even rig it to run on propane or LP, the other side being a smoker..