Awhile back Ernie L. was contemplating making a smoker from a 500 gal tank to possibly rent.
Actually, a good idea, I know of an electrician in Moline that has two different types of rentals.
The first, and most used is a griddle. He had a 1/4"x48" plate blanchard ground and made a rotating griddle out of it. Usually a 3 person operation for pancakes or sausage/burgers. The rotation is V/S and set so one person pours, one flips and the last removes. Actually 4 people work best at this, the fourth brings and re-fills beverages (for the cooks) then takes away the food. One unit easily handles feeding for 100 at a time (100 x 1/2hr x $5 to $10 ticket, do the math).
The second is like a mini Southern Pride smoker, (think bakers oven with rotating rack). I think it smokes/cooks something like 30 whole chickens at a time. I was about the size of the 500gal oval tanks with both direct and indirect heat. There are many people in the south that contract cook with mobile southern pride units and make a living (price of these can run north of $20,000). Pictures of Southern pride at: