It's truly a personal issue:
there are women here that go commando and there are women that wear liners/panties. I would suggest commando but it depends on her personal comfort level. Maybe have her try it both ways. The chamois is thick enough to absorb pretty much every thing but again it's her level of comfort that needs to determine what works for her.
and what V says - introduce her to the board!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"