Stuart,
I took the 'el cheapo' option and purchased 2 X 12v hand held pumps from Anaconda for a grand total of $25.00 (I purchased 2 so if 1 fails I'm still in the good books with the majority of my family) & a couple of shower tents ($30.00 each on special). It works a treat, either heat water on the camp fire or boil the kettle on the stove and add to a bucket of cold water (heat to individuals needs) and Bob's your uncle. A full bucket gives a bloody good shower - wet down, turn off tap, soap up/wash hair, turn on tap and rinse. I haven't had one of my long haired campers complain yet.
Mark