If I had to give a word to what I'd want to design, it would be pragmatic-libertarian. I'd want to setup a constitution with libertarian principles, except minimized and explicit whitelisted scope of the state, such that it would constrain the growth of the state both economically and socially. Any growth in scope would require some extremely high quorum. It would start out with just enough pragmatism, such that the bears don't move in. I'd want to sort out how to make a public-court that chose winners and losers based on responsibility, perhaps rather than precedence -- not sure yet. The bias would be towards defending property rights, not optimizing for 'fair'. The constitution would also have a call-back such that any law that was too long, broad, or complex would be void.

I think a thin tax layer as a base, like a flat per-person rate, plus maybe taxes on vices or taxes that are a form of pseudo-penalties for behaviors that trespass against the property of others. Example: You spill pollution in your neighbors' stream, the penalty is high for such an act, sufficient to compensate the neighbor and fund the state. Notice that property rights are defended, and responsibility is incentivized.