The best course at this point may be to back a retired and respected military leader who can unify conservatives AND others in opposition to Trumpism and Clintonism. A conservative would be fine, but far more important is a credible alternative to the current unacceptable choice.
I'm thinking about someone like Michael Hayden, a bulwark in the fight against terrorism and the general who called out Trump for disregarding the Constitution.
Something like this has been said previously and might work.
I think we are far off from an election like in Italy, where there are a number of parties running but, one can still envision some of election with the Democrats, Republicans, then, the Libertarians and then, one more party vying for the highest office.
Also, per other posts, after Trump's rise, one has to think virtually anything can happen should this Ben Sasse run; I've heard of him but do not know too much about him. I'm sure he's competent.