Liberals would not vote for Rudy. They hate Rudy because of his authoritarian and pro-war views. Ditto for libertarians. Conservatives would not support Rudy because of his social liberalism.
In 1970 James Buckley of the Conservative Party won the NY Senate race against the RINO and the Rat candidate. It's quite possible that in a similar 3-way race, both Rudy & Hillary would lose to a 3rd party conservative candidate.
More recently, Jesse Ventura won a third-party race for Governor of Minnesota. But both Buckley and Ventura were running for statewide offices, not national. The degree of difficulty, the amount of money and organization necessary to wage an effective campaign, are very different.
Running a national campaign is no walk in the park. You need time, lots of money, a formidable organization from the national level down to the grassroots, candidates with national name recognition, a solid platform upon which you can stand and articulate a consistent position and vision that will appeal to the broad spectrum of voters it takes to win a national race.
Now, it is 14 months until election day. Do you really see a viable third-party candidate emerging and running a credible campaign in that time? Because if not, I am wondering how realistic it is to endorse such a strategy.