Some time ago, reading a blog post from a libertarian who was _quite_ precise in detailing what kinds of government, and to what degree, he wanted to have, I realized that most libertarians don't necessarily want _less_ government so much as the exact amount that they could use, at that moment.

A True Libertarian would undoubtedly reply to the OP that failing to uphold a contract would be fraud, and fraud is one thing the government can police. Libertarians' definition of fraud is remarkably flexible, though, and amounts to "what I don't like".