On my 1970 27ft unit the first sw is for the outside over the door light
The second switch is for the top light over the couch and table.
As stated below you may have a sw on the curb side close to the front
window that is for an outside light on the side of the unit..
Almost a worthless light as all it dose is to shine in your eyes as you
walk up. It needed something better to direct the light down.
Dean