Landy, what do you suppose an airbag system like yours would cost me? Obviously it would be useful for more than just leveling :).
4" is fine -- I can only stack two wood blocks before they knock over anyway.
Yep, I stuff things under the mattress. Usually at 4am :(. I have a hip that fricken kills me when I sleep off level.
Other people: I am female. I run the ice machine off batteries or alternator when I'm away from power. I need leveling blocks at least half the time. Where do you camp that is so level? Pavement? Bah!