In spain take a half litre water bottle and cut it in half. The neck end will neatly fit over the beach shower head to direct water out of the neck into your water bottle to fill your tank from. In portugal all the cemeteries have a tap as some do in other countries.
It's best to look like you are parking rather than camping, otherwise passing motorists see you as a freeloader. Depends where you are wildcamping really, there are places I would have no qualms about a canopy or chairs outside, I'm there to enjoy myself!
Also so you can make a quick getaway in case the local axe murderer stops by, although I haven't had this problem as yet (obviously!).
Haven't looked through the entire post but I hope leave no trace is in there at the top of the list; cos that is just about the most important. It is top of the list for folks to whom "wild camping" goes hand in hand with human powered endeavour not just parking up in a 3.5T van...... I do that to but call it off grid camping or boon docking is quite good as nobody really knows what it means...
Don't leave your Grey Waste Water Tank tap open - Keep it closed until you can empty it respectfully - I'v seen Moho's doing this parked up during the day at the busy South Stack car park, Anglesey etc