Until recently, we carried a plastic masonry tub for a shower pan/shallow tub and used a 12 volt shower pump with a bucket of warmed water. It was fairly easy to empty into our cat litter jug gray water container. The tub has been retired since changing our layout and realizing we rarely use the tub anymore. Also, two of those shower head/pumps have given out on us. Heat is not kind to cheap plastic housings, and I don't like to replace things. Instead, we wash up between showers in campgrounds.
A litter jug is still used with my make-shift sink and sometimes outside to contain wash water. I like the size, handle and lid, and a canning funnel fits beautifully in the neck, which is sometimes helpful. Rules or no rules, we never discharge gray water.
Speaking of funnels, I recall Two Knives Katie using a canine post-surgical "cone of shame" in a bucket to control splash wihen washing hair inside. Clever.
