So it took me a few tries to get it just right (actually more than a few pillow suffered during the battle). But I finally turned an inflatable 19"x12.5" into something that's comfortable and usable! I used the Large FlexAirs that inflate with he straw and have the soft exterior 'fabric' feel.

No more head rolling to the side and crappy side sleeping. This baby cradles your head like a hockey helmet…whatever that means!

So I tried MANY variations of temperature and technique with a clothes iron with pretty results, but no real sucess. The irregular heat, and imprefect melt line failed when any real pressure was applied, usually with a slow leak from damages plastic right on the edge of the joint. If only I could have serious control over the temperature and precisely where it's applied…
My goal was originally to put one or two 'lines' into the body of the pillow to keep my head from rolling around. Obviously the lines couldn't completely bisect the outline of the pillow or you couldn't fill it. What I found was that there was a major stress right at the 'open end' of the line that would constantly fail under simulated use. So I tried instead to use a single CIRCLE in the center of the pillow, kind of like a button would be. Using some new and sophisticated low temperature controlled tools, I was able to get almost as nice of a seam line as the manufacturer with no leaks! Left it overnight with a weight on it with no problems!

Cradles the head nicely on your back or stomach. It needs just a bit more air added if you're a side sleeper to bring it up a bit higher, but super comfortable! This'll be great on my NeoAir Xlite in the Grand Canyon next month!
I've got a case of these left if anyone is interested! I'll do the hard work for you since I already made the setup. $10 bucks to you door!