I have seen some motion lights that have an adjustable field of view that could be set to only look straight down at the door so when it's opened it would trip the light for however long you set it for. And it would not come on when you are moving around the camper. That would be pretty easy to install and fairly cheap. I would start by putting interior motion light into a search engine and go from there.
2013 Rockwood Mini Lite 2306 w/Murphy Bed
2004 F-150 4.6 Liter 4x2 Factory Tow Package
2012 - 21 Nights Camped
2013 - 21 Nights Camped