I had a switch in a previous camper that I had the same issue with, had no idea what it was for and wiring was inaccessible. After awhile I just forgot about it.
On a camping trip one time,my grandson saw the switch and went over and turned it on, what kids do, turn on switches, a build in floor nightlight came on. Never saw that darn light before because I was not looking for it and it was never semi dark in the camper. Not saying that it is what your switch is for but might be worth looking into. Grandkids, just got to LOVE them. Smarter than the average adult. Good Luck in your search.
