So what I would recommend to anybody calling for an alliance between libertarians and the left (regardless of whichever side is making the call) is not look at Trump as some particularly remarkably bad outlier and anomaly (though he is certainly giving every sign he's going to be remarkably bad), but as an expression of the constantly present dangers of authority that cares only about the "right" outcomes and nothing about legal foundations and limits to power based on defenses of human liberty and civil rights.
(please do read the whole article)
Any alliance between liberals and libertarians against Trump, cannot be predicated only upon resisting Trump alone. At a minimum, must be based in limiting the powers of the presidency, and preserving due process under the law.
Anything less is asking libertarians to accept an imperial presidency, so long as it's a Democrat one. No sale.