The antonyms for the phrase "right up front" can vary depending on the context in which it is used. However, some potential antonyms could include "hidden," "obscure," "behind the scenes," or "veiled." These words indicate that something is not immediately obvious or visible, as opposed to being "right up front" or easily accessible. In terms of personality traits, antonyms for "right up front" could include "reserved," "shy," or "guarded," as opposed to someone who is open and forthcoming about their thoughts and feelings. Ultimately, the antonyms for "right up front" will depend on the situation in which the phrase is used and what the contrasting concept might be.