One way to check the position of the back leg is to look at the back knee. The back knee should be cocked in. Also the knee should be bent (forward towards the extended target line) with the back knee cap at least as close to the target line as a line drawn between your big toes or maybe even a bit closer. Moving the back knee toward the target line takes the weight off the back heel just like the "Back Heel Up Drill" does. Moving the back knee towards the target line also lowers the back hip a bit which puts the front hip a bit higher than the back hip giving the hips a little upward tilt which is a good power position.
Make sure the back knee is cocked in a bit so the back thigh is almost vertical. Most of the weight on your back foot should be on the inside of your foot mostly toward the front of the back foot.
All of this is designed to reduce the body rotation effect (i.e, spinning like a top) that tends close the shoulders at impact thereby closing the club face causing the hooks. Reducing the body rotation also makes it much easier to begin the downswing with your shoulders increasing your power.