Yeah, thats the law, and most shops are legit in not wanting to risk it.
One way around it, is to remove the tags, and trailer it to and from the shop. If you need to be more convincing, put some ET slicks and skinnies on it. I actually do trailer mine to the shop for most stuff it needs there, mostly alignments, because it is too far to drive with 4.10 gears.
This way, it is presented to the shop as an off road race only vehicle, and they are not violators. It sort of transfers the problem to you.
Or take the exhaust off and carry it to a welding shop, or do it yourself if possible.
Or, if it really is still a street vehicle, put cats on it.....
This was one of the issues that led me to a "toy only" car and all of my others are bone stock. Sales of cars like this are getting problematic also.
WD 40 works for this stuff also.