Originally Posted by MEHoffman
I would guess that switch is marked "AC only". A commonly applied "rule of thumb" is that switch contacts, relay contacts, contactor contacts and small circuit breaker contacts, which are marked "AC only" can in fact be used on DC but only at about 10% of the rated voltage. So yes, I would say that switch will function fine. DC switches use a snap contact that breaks faster as DC is much harder to break than AC. AC voltage potential hits zero 120 times per second. DC goes to peak and stays there.
It should also be recognized that this is only a "rule of thumb" and that such use may well violate the NEC or other codes and regulations.
To put that another way - as you open the switch the current arcs across the contacts, and since AC essentially turns off 120 times per second it is very easy to design a cheap switch that breaks that arc since the electricity itself is helping. Since DC stays on constantly, the switch must be much more robust to break that arc, and at high amperage you could end up with an AC switch that is fully open/off but there is still an arc inside (and whatever you are powering is still on).
That arc will quickly set the switch on fire... then your camper.
In this case that switch is only powering a few lights so it should be ok. If you tried to use it as a master disconnect and all lights were on - maybe 30-35 amps total, you would end up with a meltdown.