Ditto the comments re the versatility of an additional clothing layer vs. something that can be used only in the sleeping bag. I once tried 2 nights with a liner. I then tossed it because it took me over 5 min. to get untangled and out of the sleeping bag both mornings!
Most of us take a base layer anyway, certainly out here in the PNW mountains where it can turn from sunny and hot to damp, windy, foggy, even raining in a very short space of time. I often keep mine on (hiking clothes over it) until I'm almost ready to head out on the trail.
I recommend a lightweight baselayer top and bottom, not midweight or "expedition" weight. Merino wool is lovely but more expensive. Mine are Patagonia Capilene 2, also expensive. I got mine on closeout sales for about half price. You may end up with weird colors (there's always a reason the items are on closeout), but the base layer is generally either in the sleeping bag or under other clothing so you don't have to look at it! Watch for sales, especially at outlets. "Percent off" coupons are also your friends. Especially for tops, you may find what you want in the athletic (not camping) departments of big box stores.
Quite a few of us wear our wicking base layer tops as hiking shirts, which is also a weight-saving option.