I've done the panniers and roadbike thing. Yes, the heel strike sucks! annoyed me to the point of getting rid of the bike and buying a touring bike. Take a look at using a saddlebag instead of racks and panniers. Carradice makes saddlebags in all sizes. You can get a quickclamp that attaches to your seatpost or a "bagman" that attaches to the rails of your saddle. If you can find one that is large enough for your needs... that would be the way to go instead of racks and panniers.