Frameless pack under legs as insulation?

I'm making a similar move: from a Granite Gear Vapor Trail to its frameless sibling, the Virga. Like you, I always used the pack as lower leg insulation.

I haven't fully settled on a method yet. One option is to use a full-length pad – which also may do a better job as a virtual frame (just my initial thought, not an informed opinion – I may test it later.)

The method that attracts me currently is using a 3/4 length pad as my virtual frame and sleeping pad. If I do this, the pad is locked into the Virga by the rest of the load, and not accessible for use during the day at rest stops. So, I'm going to take a separate trail seat. It will give me something to sit on at breaks, and at night I'll put the frameless pack at my feet, with the sit pad on top of it. (I'm hoping the pack will prevent, or at least limit, how much the pad moves around at night.)

I didn't mention models because I'm not yet sure whether I prefer the Thermarest Prolite/Lite seat combo or the Z-Lite/Z-seat combo. It's a work in progress, to say the least, and may ultimately hinge on whether my 56-year-old hips can tolerate a closed-cell pad any more.

A full length pad is not an option for me; the ULA Conduit's pad sleeve is designed for Prolite 3/4 length pads. I also really have no interest in adding the weight. I know the hipbelt and shoulder straps will provide some insulation under my legs but it doesn't feel sufficient. Can any other Conduit/Virga/Mariposa/etc. users comment?

I have frameless packs by Gossamer Gear and MLD, and also use a 3/4 pad. I've never really been bothered by cold seeping through the pack itself. This may partly be because I wear very warm socks and sleep in a sleeping bag rather than a quilt (so there's a little insultation under my lower legs). One technique I've used that sounds trivial but that seems to help me is to loosely stuff the pack with my wind shirt/rain jacket plus whatever other soft items I have. This "puffs up" the pack a little and creates something of an air pocket inside the pack.

Russell:

I know you mentioned not wanting to add weight, but I am wondering if you might want to insert a piece of blue foam — say 20" x 14" (or whatever approximates the size of your backpack appropriately). Thie one piece of foam, lying flat against the back of your pack, will add very liitle weight or space, but will help improve carrying comfort. At camp, it can do multiple duty as camp chair, wind screen, or fanning up a campfire. At night, of course, you can insert it back into your pack to keep your legs comfy and warm.

Ben,

I thought about that, but the pad sleeve in the Conduit is really tight. Perhaps a small piece of a Gossamer Gear Thinlight pad would fit, but not much thicker than that.

With as popular as framelss packs are with the BPL crowd certainly someone has a good, simple solution I'm just overlooking!

I am thinking you can either insert the folded 3/4 pad into the sleeve or the blue foam pad — then lay the other piece on top, and then pack in everything else as you normally would? Not all pads need to fit inside the sleeve, right?

A full length pad can be an option. Fold it as you would a 3/4 length pad, but stand it up inside the pack so it is against your back. If you are just using the 3/4 length pad, put your feet inside the pack rather than just lying on top of it. For me when fall weather arrives, I switch to a full length pad.

I do something similar to Graeme. I stuff my windshirt, spare clothes, shoe insoles, etc into the pack for my lower legs. I use a 42 inch GG nightlite pad folded in 4 sections for my upper legs and back and my dry bag blown up is used as a pillow. Its not great for winter, where I take my DAM but for the other three seasons it works well.