Well some of the chief smoker are "top-load".. If you put couple cross beam to hold up the rack, with the box as cover, it sorta expand the distance from the heat source to the fish.
Here i think is the best way to make the true cold smoke. Buddy of mine got a big chief front load to start and he bought a bradley later on....
He drilled out a 3 inches wide hole on the side of the big chief and bolted on a pipe to fit that hole... Then he bolted a same size pipe right on top of the vent of the bradley. When the time to use, he place the fish inside the chief and put the smoker on a table with some elevation. Then he simply connect the 2 pipes with 15 feet of the "heater foil tube" and he use the bradley as a smoke generator. This way, the hot smoke with rises though the foil tube then cool down before enter into the chief. Buddy also mention, if the weather is too cold, you might have to plug in the chief to worm up the temp.. you want it just about 60 degreed.