AZ mvd says the state does not require trailors with smokers built on them to have a plate... they also said, cities within the state may have codes that address that...... go figure.....
I've never heard that one before. In fact I called the MVD not too long ago and they told me it MUST be licensed. Told them it was for competition only and not catering. She said it would qualify for a permanent plate.
If you have two or more trailers, just license one, pay for one, and move your plate from one to another. Been doing that for 20 years.