How do RV dealers do it?

Many products are sold at well below the MSRP. For RV's, I expect dealer incentives like volume discounts, etc., give them a large enough margin to offer those discounted prices and still make a reasonable profit. And that's aside from high profit dealer add-ons like warranty plans, prep charges, etc. I'm sure you've seen the car ads where a dealer says they're selling at cost and will show you the invoice to prove it. What they don't show you is how much the additional sales volume contributes to their factory incentive plans and end of the year rebates, so in reality they're still making money on each sale. There's nothing "shady" about it. They're just not opening their books up to you so you can see the whole behind the scenes picture.