W.S.
L.,
I feel for you. Have you tried enclosing part of your yard just for your dog? Like a big dog run area with a dog house and toys etc that your daycare children cannot access? And then let her out after your work day is through.
I had a border collie mix who was so energetic she would literally jump up to look in the kitchen window when she was in the backyard (and much more). Anyway I also did daycare at the time, and this worked for her since she felt like she had her own 'safe' place to be while the daycare kids were there but she could still see what was going on while they were outside playing, etc.
She mellowed into a wonderful dog after 2 years (you're right about that) and ended up being a great dog with the daycare children as well - she just needed to grow up a bit.
Anyway, please don't feel guilty if you find the right place for her and give her up - you can only take care of so many 'kids' ;-) And just think how badly you would feel if she got too excited and bit someone.
hugs,
W.