LEDs are good, though if they had wanted to conserve power they would have gone to vibration-protected flourescents a long time ago as they are even lower power than LEDs, and cheaper. The car lights they use are a standard part, of course, and cheapest of all to build.

You're also forgetting that many people are trained with the thought that after you go to the bathroom, you wash your hands. You don't open the door with them. Many people don't care but there are those who have this as an ingrained rule.

Also, the privacy I refer to also relates to the fact that the kitchen sink is normally in full view of the outside unless you close a lot of blinds. People who think of "camping" as tenting don't care but those who think of it as a portable house will feel you don't brush your teeth, floss and remove your make-up in a visible space.

But maybe you're right, maybe it's just lack of imagination on the part of the RV vendors, and the first RV to take it out and have a big shower might sell a lot.

On distillation: You could do this with propane. But I think you would get only about 10 gallons of water for a gallon of propane, which is a reasonable cost for drinking water but probably not for showering.