In Australia, it's very common to have flat-bed or aluminium trays on the back of a pickup, instead of a tub.
If you built it onto a flat bed tray, then it would be just like building it onto a sheeted-out trailer chassis.
The only challenge I see is the height of the work area. It will be at least a foot or more higher than a trailer mounted smoker.
Here's an example of an Aussie F-truck with a flat bed:
The F100/150 were a common trades vehicle in the day, and even the cops used them until the mid 80s as caged trucks to carry criminals. Unfortunately the Asian & Euro invasion has seen the Toyota hilux, Isuzu D-max/Colorado & their ilk take over that market in a massive way over the last 20-30 years. My brother-in-law used to run a long wheelbase F150 with a 12'x6' tray on it for his sign business. You can't run that size tray on the Asian vehicles.