The GOP needs people whe are simultaneously (A) fiscally conservative (to appeal to libertarians), (B) socially conservative (to appeal to religious and traditionally moral people), and (C) defense conservatives (to appeal to military and those concerned with their safety). You need all three to win, and just as libertarians are turned off by social and defense conservatives willing to spend like drunken sailors, social conservatives are turned off by things like support for abortion and drug legalization. The reason that the GOP is in such bad shape is that about all it has left are defense conservatives and everyone’s forgotten that terrorists are trying to kill us.
There are things that both social conservatives and libertarians could agree on re abortion.
Take Ron Paul's bill Taxpayers' Freedom of Conscience Act of 2009 - Prohibits a federal official from expending federal funds for any foreign or domestic population control or population planning program or family planning activity (including any abortion procedure).
libertarian Republicans would support the idea that if you are anti-abortion, you should not be forced to see your tax dollars used for abortions.
What you have nearly described is the agreement between Conservatives which is called "Reagan Conservatism". What you have forgotten in your mix is that Reaganism is unquestionably built upon a (Goldwater) libertarian core foundation, modified by a strong recognition of the Judeo-Christian ethic.
It isn't just "fiscal conservatism" which is needed to appeal to libertarians, it is the strictures imposed upon governance by the Constitution that is so very necessary to build upon. Without that very basic cornerstone, all the rest comes tumbling down.
Likewise, the mono-culture inherent in the acceptance of the Judeo-Christian ethic is equally important - Without that cornerstone, that very basic understanding of right and wrong, the universal concept of justice that is necessary for any system of governance is simply lacking. Libertarianism becomes libertine, or devolves into anarchy, without the guiding Hand of our Creator.
Without BOTH, acting as the "Conservative conscience", there can be no Conservatism, and without Conservatism, there is no America.
Reagan had it right. Without the basic understanding that it all must, must, MUST start with a libertarian core surrounded by a Judeo-Christian culture, there will be *no* agreement between the conservative factions, because there is no foundation upon which they can build that agreement.
Once accepting that foundational core, which is the very heart of what all the conservative factions conserve, as handed down from our fathers, the various factions need only to vote as you describe- voting *for* candidates that not only support their own factional principles, but taking care that their candidate will also be palatable to the other factions and will uphold their principles as well.
This is why Conservative candidates are always asked how they are able to "uphold the 3 pillars of Conservatism"... because if they cannot, they are largely considered to be unelectable. This is also why "principle" must also be more important than "pragmatism". Without adherence to Conservative principles, one is asking one or more of the conservative factions to sit in the back of the bus. They will not do so. They will rebel, and such divisiveness causes primaries like the one we just experienced.