I love my Neo Air X-Lite and have used it for a broad range of conditions. I found it fine even for cold nights in winter on the ST or cold spring and Fall nights elsewhere.

The thing is that despite temps at least as low as 18 F, the daytime highs were always at least in the 50s. Why does that matter? Because the ground was still unfrozen when I set up camp for the night. So while the air dipped into the teens, the ground under me didn't freeze.

For real winter camping with hard frozen ground with low air temps, I still use the Neo Air X-Lite, but add a Thermarest Z Lite under it.

For your route I think I'd just use the NeoAir xLite.