I don't think a person can call oneself a libertarian unless they legitimately believe that every aspect of government ought to be minimized and not expanded in any way, shape, or form -- hence why I stopped using the word to classify my ideology a long time ago, but that's just me. 
What about roundabout arguments (sort of recognizing that while the government and other individuals can infringe on liberty, the corporation is just as capable of doing so; thus, the proper role of government is to protect our liberties from both other individuals and corporations)? Roundabout arguments like the idea we need freedom of movement, so yes, the government can build the roads. We need freedom to live without being poisoned, so yes, the government can create national parks, restrict pollution, etc. People aren't really free unless they're free to actually live, so yes, the government can set a minimum wage. No one can be truly free if they are in fear for their lives, so yes, the government can fund emergency services and even some welfare programs. Government isn't the solution to the nation's problems, but it isn't so much about minimizing government intrusion, it's maximizing individual freedom through those who can protect them best from those who would infringe on them.
Well, what you said is mainly what a small minority of libertarians believe -- those being, of course, left-libertarians. Personally, I've mostly encountered the 'Austrian school-type' libertarians who seem to want to tear every wall of government down, or at least just short of doing so, so that we're living in the kind of country Murray Rothbard idealized: no government whatsoever, including a privatized judicial system. I know that, obviously, not all libertarians subscribe to the anarcho-capitalist ideology, but their long associations with the Chicago and Austrian schools makes them appear overly idealistic to me; in many ways, the Libertarian Party as a whole is much more liberal than the GOP, but it is also more conservative just for its economic platform alone.
Maybe I'm libertarian in the way that I absolutely despise the idea that we should all sacrifice constitutionally-protected liberties and privacy rights for some politician's perverted idea of "security," but that's about it.
