Warranty on a travel trailer or most other RVs is nothing like a warranty on a vehicle.
It is much more like the warranty on a house. The trailer mfr warranties the shell of the trailer. The roof warranty is by the roof mfr, the fridge is warranted by the mfr, the furnace by the mfr, etc. Heck, the axles under my TT were warranty by the axle maker (Dexter) who tried to blame a problem on Forest River and how they mounted the axles. Forest River of course blamed Dexter. Finally they both had argued long enough they claimed the axles were now out of warranty.
The Extra-Ride extended warranty did step up and pay for the repair, though read the fine print. I had to pay for shipping the new axles from Dexter to Dallas.
It would have been cheaper to just buy new axles in Dallas, have the mounting built and installed. Of course the place where I bought the trailer would not do that, because they are a Forest River dealer and have to do repairs with OEM parts.
If you feel you need a warranty, I would definitely say buy new and possibly get an extended warranty through the dealer.
Frankly it is cheaper to use mobile RV techs and pay for repairs that you cannot do yourself.
But we are full-timers. If we put the rig in the shop for a warranty repair, we have to find a motel, or relative where we can live for the lengthy repair / warranty claim cycle. Maybe you can do without your trailer for 30-90 days in the summer. We cannot.