Quick release saddle bolts?
Replace your hex seatbolt with a knobbed or winged bolt of the same strength and sizing specifications.  

Clamping knob:  

Wing screw:


(I happened to see these at http://www.jwwinco.com/products/section8/, but do not know if they are up to spec. @WTHarper mentioned the McMaster-Carr site that has lots of options.)