I use all forms of bottom insulation, and can find pros and cons to all approaches. But after 7 plus years of on and off HHSS use, I have found something I want to experiment with further: CCF pad use down in the HHSS Undercover(UC), which HH used to say was a no-no.
I have used multiple-means of taking the basic HHSS(space blanket, pad and UC), mostly adding insulated clothing under the HH pad. And on some of my far from the trail head adventures in the northern Rockies, I have always had a pad for several reasons: first as a sit pad, then as a go to ground emergency( has happened twice) then as back up with a Speer SPE to be used in the hammock if conditions went far below the HHSS capabilities. But never had to use it for that. So far, I have been able to be warm in the coldest temps I have camped in just by adding unworn insulating clothing down in the UC. It has worked great for me!
But the other day I was hanging out in my HH zip Explorer UL with HHSS. I got a sudden idea to place a full length CCF WM blue pad underneath the HH OCF pad. It was only maybe high 50s low 60s, so hard to tell the effect as I was already very warm with out this pad. But the pad seemed to be held snugly against my head, back and legs/feet, snug up against the HH OCF pad. It did not come up around or near my shoulders- too stiff in that direction- but since it was only 20" wide, it did not really interfere with the HH pad wrapping around my shoulders, plus seemed to have little effect on the way the UC fit on the sides or anywhere else.
While I was at it, I also added a shorter piece of blue pad that I use for leg pads and sit pad, but oriented in the other direction to form a "T" shape on top of the length wise pad. Since this was oriented left to right in the roll up direction, it curved nicely around my shoulders.
I'm thinking this might have huge potential for HHSS users. If it is indeed held snug against the HH pad, it could add 20 to 40 water and windproof degrees F to the basic HHSS.
Comfort wise, the pad stayed put very nicely and I could not tell the pad was there except that, surprisingly, it wiped out any slight tendency this HH + HHSS has to calf pressure. I personally don't have much issue with leg pressure with this set up. It can definitely be a problem with this setup, and some believe the HHSS makes it worse, but I can almost always find a spot where the pressure is gone or minimized. Still, adding the CCf pad below the HHSS pad gave me zero pressure without even having to hunt for the sweet spot. I was extremely warm, but hard to say how much warmer I was than without the pad. Maybe I can find out this winter!
But if this pad really will add similar warmth to what you would get laying on the pad in the hammock, but without having to do that and not even knowing it is there comfort wise, plus you get a big improvement in leg comfort, well, that is a heck of a combo right there. Especially for those who will always carry a CCF pad anyway on winter trips for various reasons.
So how about members of the HHSS club help me check this out this winter? To see if it boosts temps to the amount that seems possible? Variations to check on: just a full length, with clothes stuffed on the sides if extra warmth is also needed there, or just a short 20" wide pad under the back and the OCF pad, or one or more short 20" pads placed with long side across the width so they will roll up around the shoulders, with or without the full length pad.
I think CCF pads will work better for this, since they are more flexible along the long edges, the direction you roll them up, so more likely to curve where needed. And I suspect that the more flexible the CCF the better, but I am just going to stick to what I have, WM blue and TR Ridgerest. But who knows? My buddy uses a 55F Peapod to stay toasty at 20F, by putting his self inflating Thermarest down inside the PeaPod. This should work even better, because the Pea Pod does not have the HHSS's elastics which pull the pad up against your back. Another thing to test is just the WM blue pad by itself without the HH OCF pad, inside the HH UC.
So how about it HHSS users, especially Y'all in real cold country: anyone up for some HHSS/pad testing? ( of course you could just add the pad inside the hammock and lay directly on the pad, but then there is the comfort issue)