This easy method works for any big barrel smoker.
You need firebricks, a rectangular baking pan , standard baking pan is 26X 18 X 1 in.
May need a few bolts & washers to make support.
Arrange bricks on charcoal grate to make a fuse burn, put foiled pan between grates & fire & light one end.
My tailgating grill will burn 6-8 hrs on a load & mt 18X 18 grill will go 8-9 hours. Easy to controll temps seems to want to run 250F
Pics of tailgating cooker & a couple pics of bigger.
I'm sure you could get 10+ hours on a CG soper pro.