Thank you all!
I've been reflecting on all this for the last few days while watching DD write in low-stress situations (like keeping score in a game). I'm thinking that we need to ditch the pencil grips or all other additives to force the grip. She is so set on the incorrect grip when stressed, that the crutch just gets in the way and makes it all worse.
We're going to see about starting this afternoon by working on the magic 'c' approach timing how long she can go with the correct grip. She's been working from a cursive writing workbook, which has a lot of copying, so I might use the same approach on the printing problems.
I'm still open to ideas!