1st off - congrats on taking the plunge with the food truck, that is something I would love to do.
Another place to look is Peoria Cookers...I've heard nothing but good about their pits. When I was looking at a mobile pits last summer, they were on my short list (1st baby came in October and the mobile pit got put on hold). I live about 45-50 minutes from them and have been itching to go over and check out their stuff in person.
WSM 22.5", One-Touch 22.5", Redhead 18.5" Smoke Joe Silver, Q200, "Mr. T"