I just bought a used 2018 class C from a Gander RV that was several hours away and this was the basic outline of the transaction:
Listed online at $xx,995 "sale" price.
Call and offer price minus a few K not including tax/title/license (for me these are fixed, well known costs so I account for those mentally). My offer was pretty reasonable, I knew what I wanted and how much it was worth to me.
The salesman counters with literally the listed sale price by taking some made up MSRP (not a thing on used units) and subtracting a "discount".
I point out this fact and he starts going down the "what monthly payment do you want" baloney.
I stop him there and reiterate my offer. He says it should be possible but has to talk to his "manager" and call back.
30 minutes later they call back and accept IF I use their financing, otherwise it's $1500 more. I'll let them try and if they can beat my preapproved rate (which I was happy with as-is) then I'll go with them.
They end up beating the rate by about a quarter point so that worked out for both of us. I'll pay a little less interest and they'll get their ~1% kickback from their financing company for originating the loan.
A $295 doc fee gets tacked on which I have removed as my offer included any of their dealer fees.
Call back a day before the trip there and the doc fee came back, have it removed again.
The in-person experience after inspecting the unit was identical to any car dealer sales experience I've been through:
A lot of pencil whipping documents.
A warranty offer with several tiers priced by "only" adding a few dollars to my monthly payment.
More pencil whipping
A second chance offer at the warranty which magically became half as expensive.
I think by the time I got there they had already accepted that I wasn't going to put up with the typical sales techniques. It was very "let's get this over with" and I was on the road home relatively quickly, most of which was spent on inspection since I was basically buying the unit based on a few pictures online. The service tech that I worked with on the inspection was very helpful and I didn't feel rushed in there at all. I had time to make sure everything worked and he pointed out all the "new" systems and how they worked since I was coming from a travel trailer.
Buying new there will probably be other "mandatory" fees like destination and dealer prep/PDI they try to tack on after the fact. Kenosha isn't all that far from Indiana where the coaches are manufactured so their cost to get it on their lot should be lower than a dealer further away.
I would still approach my negotiation the same way, my offer to the dealer is inclusive of any and all of their add-on fees. They can charge a dollar for the RV and $99,999 in prep or itemize stuff all they want, I'm only paying two entities: 1) the dealer for an RV, and 2) the government for sales tax/title/license. The government fees are fixed and well known so that leaves the dealer's cut as negotiable. I think car and RV salesmen could easily lose their slimeball reputation by recognizing this fact instead of trying to nickel and dime throughout the process.
You will have an uphill battle on price by being a cash customer to them so don't give in to their shenanigans about cash vs financed price. They will definitely try to tack their fees on top of the listed sale price or your offer so be mindful of that misdirection.