Where do I place the probe for the smoker temp?

Imagine this:

The main cooking area of my (regular not reverse flow) offset smoker is 40" wide. I place some food to cook about 12" from the chimney end of the smoker. I am using a digital thermometer with temp probes (thermoworks smoke) and would appreciate advice on the best location for the probe to sit for me to accurately read the pit temp.

1. Where should it be in relation to my food?
2. Should the probe be sitting on the grate or elevated? If elevated, with what?

As i think abiut it I think my main trouble is when the smoker is loaded with meat and the probe sits between 2 cold pieces of meat and he temp seems to read much lower than it should read.....