I have this pannier, on this rack, on this bike, and I have the same problem with heel strike. I bought these half clips recently. I haven't installed the half clips yet, and I don't know if it will alleviate the heel strike, make it worse, or what. Hopefully I'll get to install them and test it soon.

I've also considered a hard-sided trunk, but I'm not crazy about being unable to tie things to my rack.