Maybe things are shifting from a sellers' market back to a buyers' market. Dealers' lots seem to have a lot more inventory than they had a year or two back.
If that is the case, there is no set rule for mark up or discount. You will have to shop and shop some more. Are you willing to travel several hours from home to get a better deal and then deal with the slower service from a non-selling dealer?
The best deal you can get is the one you will be happy with.
But do make sure that the dealer knows that you will inspect the unit and he will need to demonstrate every system on the RV. And you will not accept the unit and sign the papers on it until everything on the RV is 100%. Do not take it off the lot until every item is 100% correct. Once they have the money and you are gone, they quickly forget you exist.
Also, per the above, campsites in destination areas fill fast and RV travel is not the same as it was a few years ago. You have to generally plan your trip down to every stop and stick to your schedule. We are at the point of giving up full-time travel and leaving it to the "weekend warriors"
Ken