I've assisted with a whole pig cook on a rotisserie a few time, but it was at a friend's place. He has a dedicated pit he built for cooking pigs, deer, and LARGE chunks of beef. That's where I learned about the fire issues. He cooked a pig one afternoon for his work party and then started another the next day for his home party. Well, it wasn't cleaned out from piggy #1 and piggy #2 got really well done!
The only other pig pickings I've played at were done in a La Caja China. That's more of an oven than a smoker though.
As for cooking in a dug pit, we do that a couple of times a year at the farm, but only with small goats. Our pit is about 3 feet deep and 4feet by 4 feet at the top. I couldn't get a 200 pound pig in it, but it would be good!