When non TM shops work on your TM

In order to not hijack my own thread, I am starting this new one. When you have someone rotate and balance your tires or repack wheel bearings, how do you handle the access to the wheels since most shops won't have a clue about opening a TM and generally do not have a "while you wait" service. I do not have a lift kit so the process is more difficult.
I know some folks do this stuff themselves...but how about when you can't?

In fact, if you wanted someone to install a lift kit, how can you be sure they won't mess up the under belly of the TM since, again, you can't hang around all day to be there when they do it. Do you have to go to a TM shop only?
Cheri