1st off never let anyone run a credit check. You just bought a car so you know what your rating is. Too bad if the RV dealer doesn't get to run the credit check. If and when you decide on the model you like and price then run the credit check. Sales people are pushy but just stand your ground. We looked at several lots over the years and only had one sales person that I would call ignorant. The rest were very helpful. Even telling me that my truck wouldn't be a good fit with some of the TT's we were looking at. Good sales people are out there just keep trying different lots. Go out of town if necessary. We couldn't get a deal on what we wanted locally so we drove 300 miles to get our latest 5th wheel.
Your credit may not be dinged with the latest run of checks. It used to be that way, but now I believe that if banks or whatever lending institution knows you're looking then they realize that you're subject to credit checks. It's not your fault if you get down to a deal and the dealer is running the credit check, then they turn the tables on you and start jacking you around so the good deal isn't good anymore. Subsequently you leave and go to another dealer. Happens all the time buying cars.