That Trump’s stated position on illegal immigration is wildly impractical, racist, and vile is beyond debate. The question that is worth posing is whether he actually believes it.
I doubt it. Whatever you may say about the man, he isn’t stupid. Furthermore, as far as I know, he doesn’t have any history on this issue prior to the campaign. In all likelihood, his statements are pure opportunism; he saw how the Romney campaign profited from attacks on Rick Perry from the right in 2012, and drew the correct conclusions.