youll be able to run both element inline through the pnp controller. The only reason I have 2 elements in my little fridge smoker is because I found what looked like the perfect solution for a small smoker. I tried to put the heat source in the top with a convection oven fan to circulate the heat. Unfortunately it doesn't work as well in practice as it does in theory. The fan doesn't move enough air to keep even temps in the bottom 1/3- 2/3's.
I add the element in the bottom to even out the temp through the whole cabinient. I am likely going to take out the top element and fan so I have only the brinkman 1500 on the bottom to heat it. It will get a little hotter on its own and be just as even heating as it is with both elements now, top 1/3 may be a minute or two behind when getting to temp, but once there it will be very even.
the plug and play can only run max 15a at 120v, it would heat with the 1 1500w brinkman no problem, or any element with similar specs.
its cool up here right now and I turned my smoker to maintain 79F while cold smoking to prevent condensation and create better airflow. the pnp control had no problem at the low temp.
the pnp controller can be tuned for the smoker so that when you tune it on and set the house temp it doesn't run at full power to get the element red hot (unless you override auto tune and set to full power out) SO what it does is output the power to the element at say, 80%, when its 10F away from set temp it reduces the power output to 75%, at 5F from target it lowers it to 50% output. This prevents overshooting the temp and allowing super accurate temp control. You wont need to run a smaller separate element and pid for anything like cold smoking, unless you want to use it fro generating the smoke, but then you wont be able to do cold smoking, it'll heat the house up over 80F
you also shouldn't overload the circuit, even if you run 2 on 1 line. I have 3 elements running at the same time when im hot smoking and only have an issue when I turn all my garage lights on at the same time before my breaker blows. I have the 1500w brinkmann and a smaller element (I don't know the specs) in the smoker and another small element from a 110v hot plate to generate the smoke. never had an issue., asinde from all the lights being on at the same time and kicking the breaker only then.
get it insulated and sealed then test with just the brinkman. easy to do, and if it saves you the time and $ of adding another element and controller your ahead of just adding them.