I would guess the switch controls in-bin lights(?)
Not all bins have lights, but worth a check.
Or, if the RV has a Kwikee powered step (probably the step maker) that step light is under the RV, pointing at the ground. That light, like the step itself, has no switch and lights up when the door is opened. The step does have an over-ride switch (one of the switches by the door?) which only stops the step from retracting when the is shut and only for use when parked.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV