You can take a look at Mrs J and my setup, see the Tassie tour linky in my sig.
Heel clearance was achieved by moving the panniers back as far as they would go. Both our racks are just plain old standard ones. My panniers have sloping front sides to help but Mrs J's panniers are actually meant for the front so they have straight up&down sides. Heel clearance was a problem for her which I solved by making small stainless steel plates which moved the bottom mounting point backwards and slightly downwards. This and putting the panniers right at the back solved the problem, and we toured Tasmania like that.
If the tour pics aren't clear enough say the word and I'll post a piccie of my solution.