I disagree with your assessment.

1. There are plenty of self-inflatables (with an extra puff needed to fully inflate) that are well under 2 inches. My prolite is not even an inch.

2. Full length is not needed. I have an X-small prolite (8 oz) that I lay on shoulders to hips. I use my backpack with stuff sack of extra clothing for a pillow. I then use a 2x2 foam for my feet. (see next item)

3. Why one or the other? Why not both? I take one (summer)or two (shoulder season) square of blue foam squares (about 2x2 feet), weighing 2 oz each. Total weight with my prolite x-small is 12 oz. The blue pads double as sit pads for camp. When I take two, one goes under the prolite for extra R-factor and the other under my feet. I like this system because I am a fetal curl-up side sleeper and the foot foam can be adjusted at an angle.

4. The inflatable gives me cushion on my hips and shoulders. Having my feet dangle down a bit does not bother me. The pack rises the head area enough that I need only a very small stuff sack of clothing as a neck pillow.

I bought my inflatable at REI. When the first one sprung a leak they fixed it free. Second leak, they completely replaced it. With the foam squares I never have to take the pad out of the tent. I always pack the pad inside my pack.

If I were to use only one pad, it would ideally be a circle or egg-shaped so I could curl up on it.

PS My dog only gets a half-size Z-rest with a fleece cover.