I have a Class C with a Ford engine. It's 18 years old with 52,000 miles. I go to the Ford Dealer in Lavonia, Georgia near the SC border a half mile off I-85. It is worth the detour to go see them. They have been very reasonable and honest with me and kept my engine in top shape. They are able to get parts within an hour, maybe because an auto parts warehouse is nearby. Besides, there are numerous campgrounds on the lake nearby, so it's an area worth visiting.
I live fulltime in mine, so I asked them to schedule me for a time they can start immediately on it. They have a lovely waiting room with wifi and a table desk plus the usual cable TV and chairs. The dog and I have been comfortable there waiting on them. They have a courtesy car and have run us out to eat and on errands.
They do my work in the parking lot, but they do have a special truck lift in the body shop that they can schedule to use if the work dictates it.
For my RV "house" work, I interview mobile mechanics and see if they are interested in non-emergency work. I've found a few in several states that have been happy to work on my RV "housing" issues without charging me a 2nd mortgage. I've offered to meet them at their home or garage or where ever they work out of it, if that is easier and cheaper than them coming to me.
However, I have met some mobile guys who only want high dollar emergency work and they give no break for "filler work" between emergencies, so it just depends on each person's unique way of running their business.
It seems the RV dealers don't want my business unless I can drop thousands of dollars at a time on them, so I have given up on the dealers.
In my experience, it seems the dealers don't want to repair anything, they just want to sell new replacements, take it or leave it. Nothing wrong with that if you have deep pockets and don't mind the surgeon type rates. I am not on a generous budget, so I have to be more selective about who handles my repairs.
I recently bought propane at an RV dealer. He had a billboard inside of pricing. Like "Check the furnace-$300" and so on. I had just had my furnace repaired (it wouldn't start) and a long list of repairs done on my RV with a local mobile guy and the bill was less than that and included a lot more work on other parts too.
It helps to keep an ongoing list of issues you need to deal with. Some can wait others are critical. Overall, I think if you give them the entire list at once, you come out better than having them do one thing at a time.
RV repair pricing seems to be all over the place.
Once I find a good place or person I like, I am willing to detour in the future to go see them for the peace of mind.