One issue with racks and compact frame are the extra long rack stays that you need to reach the low eyelets, they destroy the proper triangulation of a rack and add flex.
There are a number of solutions to heel trike:
Use smaller sized panniers.
Make sure they have a heel cutout rather than a square profile.
Use a mounting system that allows some selection of position. Some locking style QR mounts slide onto an Al extrusion rivetted to the bag. You can mount the bags as far back as you like. If your load is light, rearward mounting is not too bad.
Carradice saddlebags are a good solution for S-M loads and without a rack, the whole system is a lot lighter.