That may be the case; but Repubs are not under a ‘small tent’ here. That said. . .and I truly believe; a ‘third Party’ can only mean the ‘end of ANYthing Republican - making a difference.
Everytime I hear "Big Tent", I think of the circus. Oh, wait, that's "Big Top".
Whatever...
If I am reading your post correctly, I think that you are correct in saying that (at this point in time) third parties only siphon votes away from the Pubbies, thereby handing the election to the Dims.
I've come to the unhappy conclusion that (at this juncture in history) a Conservative (whatever that means) can't be elected nationally. Just ask President Quayle.