The price is always negotiable. A special order gives the dealer some leverage since he knows you want a very specific camper. He also wants to unload inventory and if he can divert your attention from the special order with pricing games, he will. Bear in mind that the dealer gets a lot of benefits from a special order:
The purchase is off his floor plan as soon as it gets on. No cost of capital to him.
He knows you can't shop around too much
He gets immediate credit for the sale since your financing is approved at the time of order
He may be able to charge you more interest on the loan if you take one. Dealers get to keep some of the increased revenue on loans they arrange at an interest rate above the base rate approved
If you can find several dealers within easy reach who sell the same brand, pit them against one another. Get a quote for the same special order from each. Then, take the lowest bid and ask the others if they will "do better." They just might. Keep that up till you hit the lowest price. Good Luck.