I don't know about the size of the overhead lockers on the small aircraft, but have you looked at the Salsa Air Mini (not sure if still available, but you might find one. See here for details; http://www.ebags.com/product/rimowa/...-air-17/246376 ).

Failing that (or better) I think a 'Business Multiwheel' might suit you. It's not great for things like clothing, but it *is* great for papers, PC, etc. See here for details; http://www.luggagepros.com/rimowa-sa...ltiwheel.shtml

(I make no recommendation as to either of these suppliers, they are merely near the top of my Internet search results).