I think I have come up with a nice solution to label those un-marked switches, along with any other identification needs you may have around the RV.
I found an on-line supplier that will do single quantities without no minimum. They are made out of plastic, and are engraved from what looks like the same stuff that name tags are made of.
They are small too. These are 3/8" high x 1" long and about 1/16" thick. They have self-adhesive on the back.
They cost $1.70 for a single line, and $1.80 for the two line.
I also tried a single long label:
This one is 1/4" high x 3" long, but I did not like it as much. It cost $2.40
These are about the smallest labels they make. They also make much larger sizes, but these are perfect for labeling switches.
Shipping was a$3.00 via USPS, and I got them in about 4 days from ordering.
The place I bought them from was Carolina Laser, Inc -
Legend Plates | Electrical Panel Tags | Carolina Laser, Inc
For the record, I get no benefit from this - I just found an inexpensive source for labels and thought I'd pass it along.