The transmitter is going to need to be powered on any time you want control of the servo on your smoker. If you plan on smoking for several hours you are going to burn through lots of AA batteries. I'd get another power supply/converter of the correct voltage and get rid of the batteries for the transmitter. You might also look into a servo as you could eliminate the need for a transmitter or receiver, and all of the associated complications of getting everything to work together. You could probably mount the servo tester inside and extend the servo lead to connect it to your smoker. A fuze on both ends of the positive wire is probably a good idea if you go this route.