So then what is the answer and don’t tell me third party. That spells doom.
We borrow a tactic from the NRA. We tell our Republican candidates/representatives that you *WILL* do what we want, or we will wipe them out by deliberately voting for the Democrat.
We are too small to form a third party, and as you said, that's a guaranteed loss. We have to fight using leverage, and the only leverage we have is to use the opposition party against our traitors. Our weight, when thrown behind the opposition party, *IS* sufficient to throw the election against a RINO.
I have long argued that it is detrimental to the party to tolerate people who will not adhere to fundamental principles, and that in such cases we are better off with a Liberal Democrat than we are with a RINO Republican. (Remember Arlen Specter?)
Voting for the Democrat is the equivalent of a Nuke bomb dropped on our traitors. We need to make them all too aware that we will Nuke them if they cross a line, and we need to show them we are serious, by doing it. This is the tactic that has worked so well for the NRA that now they even have Democrats supporting their position and who are afraid to cross them.
This tactic works.