RidgeRest Solar

I use an old TherARest Ridgerest Solar for winter and never had a problem down to - 15°C.

As a side sleeper I sleep much more comfortable on pure ccf than on air mats. Had a Neo Air but after it failed for the third time in a row I bouhgt a Ridgerest and expected quite hard nights. But I slept better than ever. I think it's because I'm much more stable and don't need my muscles all night long to keep myself stable.

I prefer an underquilt, but when I use a pad, I use a CCF Thermarest Solar in the pad layer of my WB Blackbird.

Foam is a foam. Be it branded as ThermaRest, Decathlon or random Asian (the only difference I noticed with cheap asian stuff that costs <50% of the Decathlon's price was how quickly it gets permanently compressed). Great but bulky (more of an issue for bikers, not the hikers). I used good old Ridgerest in -5C temps with -5C sleeping bags with no issues (it was still too warm for me) but YMMV.

I'm going to have to let you know after tomorrow night. I had one of the old dark green Thermarests from probably the early 90s. R value wasn't at all a consideration. It was strictly for comfort. But I do remember being cold with that and my Moonstone sleeping bag which was probably rated for 20 to 30f. But that sleeping bag rating was survivability probably. Not the EN or ISO Comfort rating of today. Tomorrow night I'll be sleeping on a Nemo Tensor Extreme(R 8.4) and Western Mountaineering TerraLite with overfill. Overnight lows will probably be in the mid 30s. I think I've got way more sleep system than I need for that. I was actually hoping it was going to get down into the 20s or teens when we planned this trip so I can really test out my equipment. This is the first time for me to use these pieces and really modern camping equipment. Let me say a couple of things about the Nemo Tensor Extreme versus the new Thermarest XTherm. Technically on paper, the Nemo has a higher R value. But I've watched a lot of videos. There's a YouTuber in Canada named Justin Outdoors who tests a lot of equipment in very cold temperatures. He says because the construction is different between the two, the Thermarest actually sleeps warmer. If I were going down well below zero I don't know that I wouldn't have chosen the Thermarest instead. And if I do some extreme camping in the future then I may buy one of those just for that. Plus it's probably more durable. But I chose the Nemo because I'm a side sleeper and it's a half inch thicker. People generally say it's more comfortable. Of course, comfort is subjective. Try whatever, if it's comfortable buy it. I also have a ccf Thermarest Ridgecrest which has an R value of 2. If I start approaching single digit temperatures or below, I'm going to take that and stack it with my Nemo. Recently Justin has said good things about the high R value Sea to Summit from a comfort standpoint. I don't remember what the R value of that one is. But it's comparable to these others. So I think there are some good options that will help keep you warm. I don't think you can really go wrong with any of these.

I can address durability. I’ve had an assortment of ccf pads - no experience w the UL 1/8 pads tho - mostly the thermarest and z-lite. I’ve got a first or second Gen ridgerest that I bought new in 2000 that is a bit compressed now but still perfectly usable. There are only a couple little scrapes to its skin. I recently bought a couple AliExpress pads for the dogs when we go winter camping and they are much thinner and flimsier. One has a rip in it that I’ll tape over somehow. Pine needles also go straight thru them. I will treat them as disposable.