Hello. I am new to this forum, but I have had a 4 rack Bradley for 7 years and have smoked everything imaginable in it. I had the same problem you are having. I have pretty much solved it by wrapping an old solid, heavy brick in heavy foil. Prior to a smoke, I put it in a 400-450 oven. I then place it in the bottom of the smoker next to the water bowel. It evens out the temperature in the smoker and helps recovery when you must open the door. I suppose you could put it on an unused rack. I also keep a pizza stone in my oven which helps stabilize its temperature in the same way. Of course the more meat you put in the smoker, the longer it takes to recover. When I smoke 4 Butts it might take close to an hour for it to come to full temperature.
Also, I just do not try to smoke when the outside air temperature gets much below 40 deg or if the wind is blowing much. It does not matter what kind of electric smoker a guy has, outside air temp and wind will make it more difficult. I have been known to put up a tarp to shield the smoker and it helped.
Another thing to think about is if it is cold and you want to smoke, go ahead. Then when you have finished with the smoke and the meat is not finished cooking, just put it in the oven to finish. Works great and you have total temperature control. We are not purists or we would not be using an electric smoker. We want good smoked meat. Right?
Hope this helps. Smoking Canadian bacon at the moment.