There are some don't's as with not saying how much you have budgeted or what you want for monthly payments. Avoid having lots of add-on items so that a $20,000 trailer becomes a $30,000 one with all these additions. The additions are where the dealer has the greatest margins and can move very easily to discount the pricing.
A trailer that was purchased or a depot put down and then abandoned as the buyer could not get financing or for some other reason is one you can get for a very good price as the dealer does not want to pay the financing or flooring costs for the next 4-6 months.
I know if I was going to special order any kind of RV I would be paying top dollar and I would have very little room to negotiate unless there was a factory incentive to move units. Even then there is a risk if the dealer goes out of business before or shortly after the RV is delivered.
More than half the RV manufacturers went out of business in the 2008-2009 time frame with the economy destroyed by the banksters and their friends in Congress and with the economy is going to take another 10-15 years to recover if it ever does for the working classes in this country.
I always line up the financing if I plan to no pay cash outside of the transaction with the dealer. I can shop around and get a better deal that way and pre-approval is not a problem.
You have to be willing to walk away from a deal that is not favorable. I would not hesitate to drive to a higher volume dealer that was 300 miles away if I knew I could save thousands of dollars by doing so.
The cleaner the deal is for the RV dealer the more likely that they will be flexible in negotiating the price. No trade-in and cash (they don't have to quality you for financing or worry about you defaulting on the payments and their having to take the RV back, etc.) and the overall deal is a safer bet for them and with less risk they can work on a lower margin.