Even if we assumed all you wrote is true about immigrants (and it most assuredly is not, but I will concede just for the sake of argument), then the fact the majority of them are voting Democrat means open borders policies are suicidal for libertarians. If you think the fact 12% of them identifying as libertarians is a win for libertarianism, then you are hopeless. Now, if you want to discuss with me a way to control immigration so that the 12% becomes 100%, then that is a discussion worth having.
The fact that you think that if all immigrants voted for Republicans then it would somehow be better for libertarians is both adorable and deeply saddening at the same time.
And like most nationalists you miss the entire point of why immigrants vote Democrats. When the Republicans elect a violent nationalist like Donald Trump willing to violently attack and violate almost every right you have and run people like Ben Carson who talked about drone bombing people while they crossed the border, then you end up voting for Democrats out of mere survival instinct. The greatest, and most idiotic, problem with the Republican Party is its constant failures to tap into the Hispanic immigrant culture, a culture that is heavily religious, anti-abortion, family oriented, and often anti-gay marriage.
And the fact that you want to use violence to dominate how other people live act and think to grant you a political majority just demonstrates that you aren't a libertarian.
There is nothing hazy about this. Open borders libertarians have two choices: be useful idiots for the Democrats, or violate their principles in order to maximize their political power. In no way, shape, or form, will the current circumstances permit uncontrolled immigration to increase the power and influence of libertarians.