There are ways to manage the wait time. But they are all pretty dependent on having a good working relationship with the service people. They hear complaints all day long. It's rare for them to encounter someone who's nice and who is asking/discussing, rather than demanding. Which type of owner do you think is more likely to get more than "meets minimum" help?
Most dealerships have plenty of work stacked up and won't be able to look at your rig immediately. Ask what day/time they could start work and ask if you can make an appointment and bring it in at that time. Some will agree. Some won't.
Don't bother trying to get expedited service during or immediately after the dealer is having a sale. The techs will be tied up getting new units out the door so the dealership can get paid.
If parts have to be ordered, offer to pay for expedited shipping and handling from the supplier. See if the dealer warranty coordinator is willing to place an expedited order that same day. Next day air can be expensive, but it can take 2 or 3 weeks off the wait time.
After you get the RV back, don't forget that there may be a next time. A sincere thank you goes a long way. Adult beverages go even further.
Btw, in locations where business is seasonal, the dealer probably staffs to the off-season workload. That will leave him understaffed during peak season. I'm pretty sure long wait times are often a function of the staffing level and time of year. Staffing to the peak season demand would be awfully expensive in the off-season.