Measuring Air Temps Inside Smoker??

I don't have it assembled yet. Here is a description which should be helpful:

In order to wing it, I thought i would build a cinderblock single chamber smoker, using doing 2 wide x 3 long x 2 high cinderblock and this piece of expanded metal: https://www.amazon.com/Stanley-National-Hardware-4075BC-Expanded/dp/B000LNU2IQ/ref=sr_1_3?ie=UTF8&qid=1476629758&sr=8-3&keywords=expanded+metal, held in place by some concrete screws. I am planning on a plywood top and make a smokestack (interiorly and exteriorly) out of soup cans down to the mid surface of the cooking grate. I was going to line the bottom with sand in order to protect my buddy's driveway and give additional insulation, and line the cook chamber with tin foil (on top of the sand). Water pans under the meat. Coals banked to one side with a exterior cinderblock hole side out to create draft, controlled by a piece of plywood. Using hickory wood and charcoal. I hope this makes sense.

One concern I have is the sheet metal being a little flimsy to support the weight. Anybody have experience with this? I was thinking about using rebar to possibly shore it up, but I don't have anyway of cutting it to size.