I agree that you'd ideally want to use a place that does truck chassis repair and maintenance. That Chevrolet and RV dealership may (or may not) do simple oil changes and/or maintenance on a diesel pusher but dealerships like that are usually not staffed to perform any "meaningful" chassis work on a DP. Their focus would probably be more on the "house" portion of the coach.
I too have recommended Alliance Coach to others. That would be an option for you to consider.
However, I have in my notes that a small "hole-in-the-wall" place there in the Brooksville area has a very good reputation and they work on semis and motorhones along with repairing cars and pickups. The name is Dons Truck and Auto Service. They're on Ponce De Leon Blvd (HERE
on Google SV)
Facebook page HERE
You might give them a call to see if they can accommodate what you want before making the trip out of town. (352) 544-5807
edited to add: I just looked at the Register RV website and they actually do perform chassis work. Since I've never used them or have even heard of them, I'll leave it to others to comment on their reputation pertaining to their service department.