Hey Dave, We have had that shower head for 8-9 years at our home. Used to take it out to the rv when we went anyplace until I finally bought another just for the rv. At the base of the shower head handle is a knurled fitting... it will reduce the shower output to a dribble, but not complete shut off. In other words you can control volume of spray from just a dribble to full spray, sometimes full spray in the house is to much for the wife. I would try it without the cutoff. If you do the boondocking bit,, then you need a cutoff... I think they are about double normal price on that. That is good price on head unit but check Homedepot or Lowes or Walmart for the cutoff... they all have them now.
Jim M