In May, I will going with my wife and kids on a backpacking trip in Peru, during which nighttime temps may go down to -10C/14F. We are from Canada so these temps are not cold for us, but this will be our first time sleeping outdoors in these conditions as a family (besides some test runs on our deck). I think I have the kids' sleep systems figured out (Sierra Designs Spark 15 bags, fleece clothes, Ridge Rest Solar cut in half for each of them), but am still going back and forth on what to bring for my wife and I. After some testing, we found we were comfortable on our old Thermarest Guidelites (R-3.5). I had a Sierra Designs Spark 30 long (women's bag, but got it on sale at STP) and a Montbell Down Inner jacket, and was actually warmer than necessary with this combination. She had a Spark 15, fleece pants and top, and a Montbell Inner and was just fine. I'll most likely order her an Alpine Light and Down Inner pants to replace the other clothing, and cut weight and bulk.
Obviously the Guidelites at 32.5 oz each are too heavy, and I have been considering various options of similar warmth to replace them:
– Ridge Rest Solar 3/4 + section of 3/8" Thinlight under our feet – around 16 oz, nice and simple, but too bulky given we are carrying the kids' pads, plus not the most comfortable for us
– NeoAir short + full length Thinlight 3/8" – 14.5 oz, lightest option, but at these temps I'm a bit worried about the NeoAirs deflating as the air cools, and losing warmth during the night (comments from users are welcome if you have any thoughts on this)
– Prolite Plus short + Thinlight section – around 18 oz, so heavier, but I know we are comfortable on this style of pad
I was leaning towards the Prolite Plus, but then I thought about using an Exped Downmat 7 instead. I noticed some users saying that switching to a Downmat 7 allowed them to take a much lighter bag (some claim up to 15F lighter), so that even though the mat is much heavier than other options, the overall sleep system ended up being substantially lighter. The cost investment would be worth it, as I would use one of the Downmats as a winter pad, and likely lend the other to trip partners (since my wife is not yet interested in snow camping).
Using a Downmat may make it possible for me to take my JRB No Sniveller, and my wife to bring the Spark 30 I was planning on using. The Downmat XS would weigh around 22.5 oz each including a Thinlight section for our feet, which is 6 oz heavier (each) than the Prolites. However, this would be offset for me by saving 6 oz on my bag, and for her by saving 9 oz. Plus, the added comfort of the Downmats would be a very attractive feature.
On paper it makes sense, but I have no idea whether the additional R-2 to 2.5 of insulation would offset the warmth lost by switching to lighter bags. Also, both my wife and I switch between back and side sleeping during the night – I imagine that when side sleeping, the Downmat would not provide as much compensating insulation as when on our backs. I am going to try calculating the clo values for each of these setups, but don't have the energy for it right at the moment (will have to wait till the weekend for this – unless Richard Nisley decides to chime in!). In the meantime I'm wondering if anyone has any practical advice to offer on which of these options makes the most sense – or if there's anything else I'm missing.
Thanks very much for your thoughts.
