Reverse flow offset! Size the firebox right and get the fire management experience and you should be able to get 2-3 hours sleep before feedin-the-beast during those long & slow cooks (a remote thermometer with an high/low alarms helps too). And properly sized firebox, inlets and exhaust will let you cook in the 300*-350* range if you want (i.e., brisket in 6-7 hours). Best of luck with your build!
PS: a 500 gallon tank is big enough for whole hog if you design your doors right!
Weber 26.75 OTG w/CI grates & SJ/WSM Mini
Home built 24"x72" reverse flow stick burner trailer with 18"x44" grill w/CI grates and upright SS gas oven/smoker.
Home built 48" fire pit with a 30"x30" Santa Maria style ranch grill.
Home built lump charcoal retort, iGrill & a bunch of other cooking toys.