I think your dealer gave you the standard line about making nothing. My kids won't eat, you raped me, i'm entitled to make a living, don't you have a conscience, is your name Lucifer, etc. They make a ton on the motorhomes, a little less margin on the trailers, but still a huge profit compared to an auto. This can be comfirmed by the residual market value in the NADA blue bok after one year.
Last word I had was that the margin was about 25-33% on the Airstream Safari, but I tend to believe the lower figure. I can't say if the dealer also gets a "holdback" percentage of the stickerprice.
I bought my 1999 Safari new in 2000 at Minnesota's largest RV dealer (an Airstream dealer) after they sat on it for almost a year. I got it for $9,900.00 of the sticker and they were still smiling. I called several other dealers and asked if they could match it and they said yeas, but they would not make anything on it, so I figure I was close to cost on the deal.
That said, supply and demand are powerful and as Jack said, they don't make very many. I was in the right place at the right time. I'm not so sure I'll be as lucky the next time.