Ok..to avoid a mess this is what I do...

Get a cheap plastic table cloth or shower curtain from the Dollar store, cover it with a soft sheet, tuck it in and when the urge to flow happens, just let it go, worse thing that happens is that you have a little bit extra laundry but what the hell, the feeling is well worth it.

I truly believe that all women could do this if they let themselves go, but like you they think its an urge to pee, so go pee before you get down to business, then when you get the urge you know that it isn't pee but that sweet/salty clear stuff.

Good luck