Paul,
Unless you ride in deep water that constantly splashes the sides, I think you will find most of the water gets in from the baffle at the bottom, and the openings at the upper front corners. The door on the '03 was handy for checking the filter for proper seating. Bottom of filter wet? Cut foam rectangle blocks about an inch thick for a slight compression fit in the well over the baffle. This keeps splash water out but will allow any that gets in from the top to drain through. I cut a few and cleaned/oiled/changed them when I did the filter. I taped up the corners and had no problems.