I guess I would ask first what the opinion of your vet is. If it's a conformation issue, I've had ASL dogs, especially long legged ones, that have been down on their pasterns until they build enough muscle mass to straighten their legs. This causes them to walk on their heels until their pasterns come up. Hope that's some kind of answer!
'If you find a way to enjoy the ride, it doesn't really matter where you end up'
5 GSDs at the gate: Katie, Iroc, Red, River, Jake