Downmat vs self inflating + closed cell for winter camping

I am wondering whether I should be looking at a self inflating mat (Torsolite, T-rest prolite plus) with a closed cell foam mat.

That kind of combo works for me … short T-rest Prolite 3 and a 72" RidgeRest or blue foam. Prolite to be replaces by NeoAir by next season.

But at temps much below what you mentioned I tend to go with two closed cell pads, especially if on snow.

I actually think it is the perfect combination for both warmth, padding, weight and durability. At around -5C and lower (or on snow or frozen ground) I will bring a full length Ridgerest and put the torso pad (prolite XS) on top (20 oz.), otherwise I use a cut down 36" Ridgerest and a torso pad (14 oz.). You can deflate the torso pad a bit and get the shoulder and hip hole effect and it is the most comfortable sleep I have had even on solid rock or wooden shelter floors. If the torso pad deflates for some reason I still have at least some pad underneath me.

I had a synmat, then I bought a neoair, and I think a neoair is more comfortable. I think its the smaller horizontal tubes compared to the long tubes. If you are a side sleeper you will like it.

If you only want a short pad you could go with a slightly trimmed walmat blue pad at 4 oz or a GG 1/8 pad at 2 oz and a small neoair for a total of either 11 or 13 oz depending. That should give you a R value of close to 4 with a blue pad.

If you are in some seriously cold weather then I could see the need for a downmat or a synmat, but they are really heavy.