Based on your new truck being 15 years old, I'm going to guess that a new camper will be a significant purchase for you, financially speaking. That said, new vs used, for you, I don't see why you need to spend the extra dough on brand new.
The way I see it whether it's a camper, truck, toaster etc. usually some bugs to work out that the warranty covers then with a camper, in a year the warranty is gone (maybe they're longer, idk) and you now have a pretty new camper that you paid full retail for and no warranty left.
Prices of high end TCs are ******** for what you get imo. Wrong time of year to look for used at good prices but they're still way cheaper than new. And if you go private party you can skip the dealer bs.
Financing wise, again my opinion, but if you have to finance it, you're not rich, so save $10-20k and find a new used one.
If you do go dealer, get some financing secured before hand. Credit unions are better than s&l imo. Figure out what a couple banks will do for you so know what to push the dealer for.
Here's the deal. If you finance w your own bank the dealer gets a cash deal so no more money to be made after the sale. It's a cash sale to them.
If you finance through the dealer, I'd guess some finance in house so they're making more $ throughout the life of the loan and even if thy use a bank they still get a cut of the deal. Typically you can negotiate a better sale price if the dlr is financing. Also make sure the financing can be paid off early without penalty. Then if you have a Better bank deal you can let the dealer soak you on interest rate and you stick to a lower purchase price. Then refi it right away with your best preferred rate after purchase.
That's my 2c.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold