[KeithInUpstateNY]

A couple of thoughts after reading through the thread and the advice you've received so far.

If you are serious about wanting to consider "winter" camping a trailer with slides will make that more of a challenge for a few reasons: more exterior surface area per square foot; the insulation in the slide walls, floor, and roof has a lower R value than the main body of the trailer; and you have a gap around the slide with NO insulation, just rubber gaskets. A longer trailer can give you the same square footage and be easier to heat (or cool), but they don't feel as spacious because there entire box is only eight feet wide.

Speaking of longer trailers, if you plan to spend a lot of time in national parks you may want to limit the length because many have length limits.

You also mentioned wanting something durable. In "light weight" trailers the floor is typically a sandwich of thin plywood, foam, and another layer of thin plywood. They seem to be especially susceptible to water damage. Some trailers have a product called Azdel in the sidewalls. A sheet of plastic replaces the luan making it less susceptible to water damage. Unfortunately, I don't know if any trailers that use it in the floor construction. If anyone else in the thread does I'd love to know about it.

Finally, you mentioned storing the trailer in New Hampshire. That's another reason for a walkable roof, they can carry a heavier snow load.

Good luck with your search.