Have you tried Water's Edge Farm? I believe it's in Sykesville... heard good things about it a few years ago when I knew people boarding there. The main trainer may
have left, but I'm pretty sure the farm owner is ICP certified, too.
I think I remember you mentioning that you're on the boarded of Howard & Carroll counties - how far is Full Moon Farm from you?
If I think of any others, I'll post again. But definitely hope to hear back from Gretchen - I've had XC lessons with her before and she's wonderful!