This thread sure has gone off at a tangent from its original intent!
Getting back on track, one of the things added to my Airstream after about the second camping trip was a doormat, to minimize the amount of dirt tracked inside.
And I also included a collapsible washbasin, that I can use to carry toiletries, towel, and a change of clothes to the public showers in campgrounds that have decent ones. The washbasin serves double duty in the galley for post-meal cleanup, since my Interstate has only one (small) galley sink.
Engineering: Finding complex solutions to simple problems you didn't even know you had.