Even if you had a perfect corruption-proof government design... What can you do about it? You are not in charge, and have no way to influence the people in charge.
Even if you had a perfect corruption-proof government implementation, you still have humans composing that government, and therefore it won't be corruption-proof for long.
I don't think a design could be said to be "corruption-proof" without taking into account the elements that compose it. That may or may not be most of a proof of the non-existence of "corruption-proof" government.
