I never have. I think the dogs know that biting me won't change my attitude. Not to say that it won't hurt...but I've definitely hurt myself more through my own carelessness or stupidity than they ever have. Ever given yourself a concussion? I have, lol. I could go on, but it would be embarrassing.
Why can't you put a muzzle on Zeeva? I have a DA foster here right now, I believe he's FA because he's fine if my dog isn't invading his personal space. I do muzzle him on occasion, if I'm taking them both out at the same time. Just in case my dog disobeys the "leave it" command. It's a really nice basket muzzle, and he doesn't mind wearing it at all. Why not try that, it's a good first step and will take away some of your uncertainty.