When I am cold smoking with my A Maze N Smoker or with a soldering iron in a tin can I am not using a thermometer at all since they put off little to no heat in your smoker. When I am cold smoking I am going by time not temp. When when you are hot smoking I would suggest getting a wireless dual probe thermometer. It will have one probe to monitor the temp inside your smoker and one probe to put into your meat to monitor the internal temp of the meat. When hot smoking you are going by temp not time. Its done when it hits the targeted internal temp. These dual probe wireless thermometers have a cable that go from your probe to your base unit. They can be put right in the smoker and run out the door. I use mine in my oven all the time. That way you don't have to drill any holes or anything in your smoker. Just a thought.
Here is the one that a lot of us on the SMF use. Check around and you can usually get them cheaper than on this web page.
The range isn't the best on this thermometer but it has a high and low temp alarm which I like for over night smokes. There is also a thread on how to mount an antenna onto the unit and improve the wireless range.