I started with a Coleman camp stove for heat and kept running out of gas, so my current rig is:
LP "turkey" burner, (fed by 20lb tank), 5 gal recycled metal gas can on burner, 3" fitting attached to top of gas can, 3" plastic pipe straight up about 18" to a 12"x12" x 5" cedar box. The box can hold up to 8 -10 ribs at a time. The box is on legs so it's easy to set on or off the steam pipe. Works great.
The best system I've seen was at Stewart River canoe shop. Alex uses a std elec (?) water heater to generate steam, hard plumbed so refilling is easy, just turn the valve on and watch the site glass, the steam is then sent to either a box for ribs or tube(?) for rails.
Dan