I have size 14 shoes and ride an older 'sprt touring' bike for camping and short tours. I've only had heel strike be an issue 1 time and it was on 1 bag. I just reset the bag on the rack and was good to go.
These are combined 45L bags, so they are hardly small and the chainstay isn't some loooong length.

Get an Axiom rack that has a lower bar that is long. You can adjust the bags and have more options for where to place them. Other racks with a sweepback design should be fine too.