Well, most insurers have substantially different policies terms for work use vs home/recreational. For one thing, they know the risk of a lawsuit is greater and the potential for a jury award is as well. But there may be a subtle distinction between "living in the RV while you work somewhere", vs "using the RV for work". If you don't actually do work from the RV or park it on a job site, you may not fall under the "work" definition. Of course, using the RV as a fulltime abode will also involve higher premiums than part time recreation, but it's usually not a big difference.
It is nigh impossible to compare insurance rates among RV owners - far too many variables for it to be meaningful. You need to shop around and get some quotes from other insurers.
You didn't mention the coach or the car year/make/model, so its hard to even guess if the premium seems high or not.