I was a registered Libertarian until after 9/11/01. I was very dissapointed with the anti-American, leftist propaganda I saw coming from many in the LP after the WOT began. I decided to become a Republican after reading Larry Elder's chapter on why he switched to Republican (in the paperback edition of Showdown). He talks about just what you mention,essentially being able to do more from within a party with some actual power.
Now that you mention it, the two types that are ripe for going to the head of the class in the Republican Party, are the libertarians and blacks -- and they should be aware of a ready-made opportunity that already exists. Instead, many insist on beating their heads against the wall and ranting to a universe that isn't listening -- because they think it's just another demented, liberal rant -- not meant to talk to anybody in particular, not expecting to be taken seriously.
But there are situations that are ripe for their success -- overwhelming success -- if they can just take off their blinders and consider all the options and choices available to them. It's easier to be a practicing libertarian than to try to enforce it on everybody else -- which seems to be a failing tactic. But there is easy success for them in just living their own ideals -- rather than in trying to convince everybody else that they are "right," before they themselves can live that way.
That's the failing of the left -- and every other movement for that matter. Living one's ideals is a whole lot easier and more practical than first convincing everybody else you are "right," before you have the courage of your convictions to live that way.