I think that NRALIFR is correct. Companies with commercial towing licenses are not going to exceed the height restrictions.
The only time they might take the chance is a short run where they know they can make without tearing down something. Maybe a pop-up camper would clear but I think a full hard-side would be too tall in most cases.
I have seen medium duty wheel rack tow trucks doing the job once the driveshaft has been disconnected.
If/when you make the magic call to any roadside service, make sure whoever answers the call understands what a truck camper is " . Inform them you are at 11-12 ft tall and 12,000# . Tell them you need a med. duty front wheel tow. Not a flatbed. I have seen flatbeds respond and have to make a U-turn to go get a different tow truck.
