I wonder if there is some confusion on wording here. To me, the right hook to the head, the right cross and the over hand right are one and the same. That punch, thrown to the head, is, truly, a very situational punch, depending on position. I like to teach it,especially to shorter fighters, to be thrown in a spot where they've turned to their right (my left) and have a blind side angle. Toss it over the foe's shoulder: his natural inclination, to you circling to his blind-side, is to turn to follow you. Turns right into the punch.
Von, does your coach give you positions with the mitts? By that I mean, does he hold his hands out or does he make you work with his body? Does he make you, for example, throw that punch over his jab? My advice would be to keep practicing it until it becomes natural to you. You have to consider the placement of weight on your left leg in the context of the way you have to move that leg to get in position to throw the punch. In other words its generally a shorter step to slip the left and punch to the head than it is to slip and hook the body, with the right, anyway.