Good luck with your event Badgerdaddy - it looks like a good one, and if I lived closer I would certainly come for the race.
As for the shower issue - no matter how careful you are as an organiser the showers are going to get skanked up, from soap, shower gel, shampoo and general footfall as 100's of people pass through, its just inevitable. When I see the hideous state indoor toilet facilities are left in after (and very often just before the start) of some races, toilet paper all over the floor, water (and worse
) everywhere, then I can pretty much guarantee you will have a lot of cleaning up to do as the day goes on and certainly after the event. People are generally skanky feckers, so just prepare yourself for the worst
.