Non-free standing tent for JMT

Ok, so even the GG pads + the RidgeRest would be only a 3.6 R value – still 'undesized' in your opinion.

Even the NeoAir pad has only an R value of 2.5. I'd have to combine that with my RidgeRest, or get a 2nd RidgeRest.

Is there a combination you suggest? Or a pad… I'm open to buying some additional equipment for this trip.

Many do well with a Thermarest (prolite) on a foam pad for winter. Some like the down mats in spite of the hit on weight.

Chart on R Values of some pads: http://sectionhiker.com/2009/03/27/sleeping-pad-r-values/

Winter camping thread: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=17199

Balaclavas are nice and warm.

You may not be going out into the deep freeze… but with every day closer to winter, risk increases. Our local SAR just pulled a dead hiker out of the Edison area, which is where Vermillion Resort is, just off the JMT. His friend who survived has frostbite. It's not even that high, or that snowy, and they probably weren't well prepared as you, but. Please be prepared as you can. It may be that you have a great sunshiney time, and you'll curse us for our paranoia, but it's better that than the other way around.

Supposedly, what's under you is more important than what';s over you, all factors being equal. A lot depends on how warm (or cold) you tend to sleep.

This time of year, I'd go with a Thermarest Prolite Plus (1.5 inches thick; R = 3.8) on top of a 1/8 inch Ensolite CCF pad (<2 oz for 20×72). The pad length does not affect the R value, only the weight. The ensolite is there mostly to protect the inflatable, but does add a bit of insulation from the ground in case your inflatable is less than full length. Also, if your inflatable DID deflate, you'd still have some insulation under you.

Another alternative, the Big Agnes Insulated air Core pad. At 24 oz, it's heavy but the 2-1/2 inch thickness (R= ) is worth it. Again, I'd protect it with the 1/8 inch Ensolite pad. The BA pads are on sale at REI right now for $60 (regularly $80).