Water usage is not something we've ever felt the need to restrict, from day one the whole 'raison d'etre' of building the trailer and now the Mercedes conversion was and is to provide as a bare minimum a decent toilet and shower. We've slummed it too many times to not want them, even if we are miles from anywhere.
However frequent or infrequent your lovemaking may be, getting too regimented over 'where and when' tends to spoil the intimacy of it, all you need is your chosen lubricant and a box of tissues, shower afterwards or in the morning. Youngsters probably don't need the lubricant. In our case no condoms either, I had a Vasectomy back in the early 80's when both of our sons were well grown.
Yes, blokes tend to relax and have more time for intimacy when on holiday, is that surprising?
Most of the other stuff is OK, but is it such an issue to wash up 'normally' ? We use a fair bit of water, we have three 40L Aquarolls, but don't find it a big issue to wash up in a sink once or twice a day. We don't waste water either.
I did appreciate the input from the OP, it makes a nice change to get the feminine viewpoint on such things.
Peter