You forget that libertarians want to defeat conservatism, they aren’t looking for candidates who are “more” conservative.
It is real simple....
I am going to vote for the small government candidate every time. If there are two small government candidates then I will vote for the one most likely to defeat the statist. I don't give a damn about which party they associate with. It could be Socialist Vs Constitution Vs Libertarian or Democrat Vs Republican Vs Green or Labour Vs Conservative Vs UKIP. I don't care. The candidate that advocates more forcefully (and believably) for a radically smaller role of government in our lives gets my vote. Understand, when I say "smaller" I don't mean "smaller than a fascist tyranny". I mean smaller like how the founders designed it.
Looking at the majority of Republicans now a days, I don't know if I will ever get the chance to vote for a Republican ever again.