We're in the meanie bunch too - my girls get a jug of water tipped straight over their heads to wet and then rinse their hair. The jug is my old plastic measuring jug that is now their permanent bath toy as well as hair rinser. They actually like it though, and now "rinse" each other's hair.

Is it more the actual act of lying back that's upsetting her though more than water on her face? Both my girls went through a stage of not wanting to lie back (which is why we started using the jug). Now they're back to both being happy doing it, but I still find the jug easier.