I recently bought a used boat. The head stinks. I've pumped the holding tank
a number of times and I've tried cleaning out the system with a variety of
off-the-shelf head cleaners. This has helped, but I still have more odor than
I would like.

Would it help to clean out this system with a diluted bleach solution similar
to what you suggest for the water tank? Any suggestions would be helpful (I'm
resisting replacing all the plumbing hoses unless I absolutely must do that,
but I something short of that will work).