I don't think I would use either filter. Just put a dew/light shield on the front of your scope and go from there. The OIII filter is a specialist filter that works on some nebulae and actually makes the view MUCH worse on most objects.
As for the moon filter, its not suitable as well.
If light pollution is a problem just limit yourself to the brighter objects........ Saturn comes to mind.
Good luck
and have fun.
P.S. Use your cheaper eyepieces for public viewing definitely not your Pentax one.