RAGBRAI was a good example that there are lots of riders in your boat-
cornfields on either side of the road marked "His" and "Hers", complete with toilet paper on a post!
I'm a four-hour or more girl myself but have no prob with going in and undesignated potty zone if it's that or my shorts!
Lucky, I've not had that situation on the road. On dirt I pay attention to the lie of the land and pee facing uphill so's I don't get my shoes wet. Oh, this has actually happened to friends-watch out for poison ivy and stinging nettle. 
I want to know why is it you always have to pee while in the starting line at a race?
I used to have an open mind but my brains kept falling out.