What a labor of love...
While these pants are not cheap they will stay on and you just insert a pad or cut up a depends to put in her panties. I have a friend who has a very old yorkie and she takes the xxs and they fit him and stay on all day/night. It will make your life a little bit better. You might write a letter to the lady and maybe she would give you a discount.
Piddle Pants For Dogs
I know someone on here had a little yorkie that needed a cart and I will search to see what I can find on where she got her's.