Joanne- have you ever heard of a bathing tether? It has suction cups that attach to your shower wall which allows both of your hands to be free to do what's needed. Here's what 1 version looks like.
http://www.rinseace.com/images/bathingTethers2.jpg
I also found this which looks like it may work better for our smaller dogs
Dog bathing: Bath-time supplies: Pup Tub at Drs. Foster and Smith
Good luck
Sherry