I have the identical issue with my racks, although my current pannier doesn't use an elastic hook system, so it's not an issue for me. I've been thinking about getting a new pannier that does use a bungee hook system, and I just thought of something. Couldn't we just use a picture or mirror hanger and use it like a washer to the bottom pannier bolt? There are so many types of hangers that you could get whatever hook works for your pannier system. Like below:

http://www.acehardwareoutlet.com/(lp...px?SKU=5061585
http://www.acehardwareoutlet.com/(lp...px?SKU=5109509