Standard ¾

I have a thinner version of this and I can’t stress enough that it is self inflating!! Open the valve and let it sit to fill with air. Don’t put anything on it. Once full close the valve and set up everything. When folding and rolling away open valve get all the air out and close valve to seal. I have seen these where the owner would blow to fill it up and they get moldy and stinky fast. Also store it unrolled and open valve, I put mine under my bed.

So that sleeping bag will not give you much warmth when laying on it. If you are feeling that much cold from your pad then yes you need a better pad for the cold. I personally never experience this, but everyone is different with the cold. You seem to run cold if you had all those layers on while sleeping. This is just one of those weird things with people. In those temps I would sleep in my underwear with a 20 quilt. My buddy would be all snug with full sleepwear and his puffy to start out. Everyone is different for cold. I have used the standard thermarest for about 10 years.

I started on the old school thermarest shortie, then a full length, then switched to a big agnes inflatable--which i liked but went through two of them with bad valves. Switched to a nemo a couple of years ago, and love it. It's a little "crinkly" sounding, but otherwise well worth it. Good choice :-)

We use Thermarests or their equivalent from like REI. ¾ sized ones to save some bulk.

I've had great success with Thermarest, REI, and Exped self inflating mattresses. All have good customer support too. I wouldn't ever bother with an all air mattress. Poor insulation, rotten in cold. Get a FlexTail pump.

I use my full length R4 self-inflating pad all year long. For sub-freezing temps I add a 3/4 length R3.2. I use a 20oz "emergency blanket" (tarp with mylar side) as a ground sheet for bivouac, tent footprint, and emergency shelter.

You want a good, insulative mattress that is easy to blow up since they placed a restriction on the situation. I recommend a Thermarest self inflating mattress as best suited for a child that may have difficulties blowing up a non-self inflating one. Or, get a footpump. It's pretty straight forward. If you have more specific questions about how to operate one, ask away (open the valve, wait a bit, close the valve or add a few breaths first).

So…I went from an inflatable mattress…no insulation, to a cot, with a thermarest self inflating mattress. Better, but I found the cot to be so confining. Ditching the cot and using the thermarest on the ground was 100% better.