In terms of buying new, the dealer's willingness to take a smaller profit increases as the trailer sits in inventory longer and longer. Dealers don't "buy" inventory outright. They have a "floor plan" which is a line of credit usually extended by the manufacturer. This line is like any loan, there are interest charges. Most floor plans offer zero interest for a certain period of time. With many cars (varies by model, season, etc.)the manufacturer gives at least 90 days of interest-free time. If the dealer can unload the vehicle in less than 90 days, they get to keep all the profit. If the inventory ages past the free-interest period, then the dealer is paying interest until it is sold.
Trailers are probably the same. I don't know for sure. I do know that manufacturers need to make new trailers 12 months a year and they can't afford to just stack this inventory up at the factory. So, if my guess is right, they give dealers the inventory interest-free until some time after the "season" starts. This gives the dealer an incentive to stock up early.
The dealer has no real investment in trailers during this time. If they can sell them early, so much the better (the credit line has limits, so if something new is introduced, they want some available credit so they can add the models). You can make the best deals on inventory that is just approaching or is past the time the dealer gets it free of interest.
I know I didn't get the lowest price for my TT, but the dealer has an excellent service department that has worked hard to make things right for me. It's worth the extra money to have that. After all, problems come up when you want to be using the TT. Having a dealer that makes sure you get back on the road quickly is worth a lot.