JR Enterprises is well known for large bbq pits, but recently the guys from Arkansas introduced a four shelf towable rotisserie smoker that looks very interesting.
The shelves are 10 x 44 inches and, according to the website, are capable of cooking 16 slabs of ribs or 20 pork butts. The smoker has a bottom drain for easy cleaning. Also, I have it on good authority that the smoker weighs 860 pounds and is available with optional 15 inch wheels and tires to make interstate towing a possibility.
You can learn more about it at JREnterprises.com.