I realized today that this is a problem we all share, and that my solution may not be very common, at least in the States. So I thought I'd share.
I use a portable bidet, similar to
this one. It's not very good as an actual bidet, but it works great in the shower if you don't/cant have a detachable showerhead.
Dirt cheap and no more mooning the showerhead! Hope it helps someone.