That looks like burnt fat. Like you said, the fat is dripping onto a hot surface, burning, and the smoke is wet with fat.
If you can find a way to catch that fat, or divert it away from the heat source, it would probably reduce the amount of fatty smoke considerably. One of the primary reasons I use water in my drip pan is so fat doesn't drop into a hot, metal bowl.
Having a top vent to allow smoke to escape would help, some, but won't completely eliminate the goop accumulation.
Can you get those things hot enough empty to burn that goop out? Or, maybe get some weed burners to burn it out. You'll probably need to turn that goop into char, then take a wire brush to it.