I had a friend back in TX who has a deer processing bus. that does close to 15,000 deer per season. I took him a bunch of crappie & white bass gutted and washed only and did em on the racks the sausage hung from in his smoke sheds using mesquite. Layed em on the racks with belly flaps open/down. Excellent.
As a kid we had an old fridge we took the door gaskets off cut a hole in top for 4" stovepipe/flue, cut about a 12" hole in the bottom and dug a firepit
with a short 12" wide tail (trench) coming a couple ft off one end of it. The bottom hole of the fridge sat over it, the firepit was to the rear of the fridge and kept covered with a piece of sheet metal, kept askew just enough to allow air flow. One wire rack was left in the very bottom of the fridge and we put a cpl rebar running crossways near the top. We smoked carp, redhorse, buffalo (fish) in it. Gutted them and washed very very well then hung em on the rebar by hooks running thru both eyes. When the bodies fell away from the heads the fish was done smoking, would pile up on that bottom rack.
This was an old-style fridge that had the motor underneath (removed).