Buying from a dealer questions & negotiating questions

No negotiating. You want to make an offer for an out the door price. Dealers have ways of adding stuff in to boost the price and make you think you got a deal.
The only add on that should be allowed is ACTUAL DMV fees and sales tax if you want.
Do not know how far you are from him but there is a guy from Texas named Doug Rainer on this forum his advice has been right on so far and I believe he still is in the RV business.
You might want to PM him and maybe pay his place a visit.