The antonyms for the phrase "bare heavily" would be something along the lines of "fully covered" or "heavily clothed." In essence, the phrase itself implies a lack of clothing or covering, and therefore its opposite would be the opposite in terms of covering or clothing. Other potential antonyms could include "moderately dressed," "dressed conservatively," or "lightly clothed." These antonyms all imply a level of covering or clothing that is opposite to the complete lack of clothing suggested by the phrase "bare heavily." Despite their differences in wording, each of these antonyms conveys a sense of modesty or conservatism in clothing, suggesting that the wearer is covered and protected from the elements.