re inflatable zafus: zafu.net has one, which supposedly can also be used as a (supplemental) bus and airline seat (may be quite helpful for our bus travels) and pillow or knee cushion for sleeping or using the supine position. Not sure how stable they would be for sitting (I normally use a portable kneeler rather than a cushion).
Just received a thoughtful Christmas present from my beloved wife of 40 years -- an 8-oz. gel-filled Comfort Cushion (www.skwoosh.com) which seems an even better airline/bus/auditorium seat cushion than the inflatable small air mattress pad I've customarily used (I've also light-heartedly used this air mattress at lectures as an example of the "small raft" that "Hinayanists" supposedly use ;-). This Skwoosh product may also make extended chair-sitting more comfortable, although I haven't enough experience with it yet.
I still plan to take the small air mattress with me, after experiencing how nice it works on some of the uncomfortable beds I've slept on while traveling. It can also be used as a supplement for the supine position as well.

I am scheduled to arrive in New Delhi at (yawn) 9:45PM on Sunday 31 January, which is close to the arrival time of others. We may have enough to arrange a larger van or something similar.