Here's an idea - a bean bag "tripod". Haven't tried it myself, though it's gotta beat using a jacket:
http://www.amazon.com/Pocket-Adjusta...7016351&sr=8-2
I picked up a Tiltall Traveler - seemed ideal for what you are looking for. I thought they were phasing them out at $99.99 but seems they are back at 159.95. Only issue - the lock on the neck stripped the 2nd time I used it.
http://www.amazon.com/Tiltall-Sectio...7016516&sr=1-9
/Mitch