My DH has always had the same problem with his heels hitting the spindles. He has very large feet and toes out. He has used both Speedplay X-2s and Zero pedals and still has the problem. Kneesavers worked for him. They may not solve your problem, but they are an inexpensive solution compared to some of the others, if they do happen to do the trick for you without being too much.

Good luck, ny biker!