I have some advice: stop heel-striking.
Throw out your VFFs, do some actual barefoot runs, your mechanics can't be that awful (or you can't be so hard-headed) as to heel-strike when barefoot. Mostly because it hurts and your body will adopt.
Bend your knees, think about having your hips over your knees as you land, head forward, torso up, etc. It shouldn't feel like you're uncomfortably trying to hold this position though, it really should be natural.
Nothing was more natural to me than mid-foot striking when barefoot.