Sadly we just plop the shoes right by the door--usually to the right of the door up against the "step" to the front.
As far as the PP..not sure. My inclination would be to say "try it". You're already putting chemicals/enzymes down there to break things down and minimize the smell anyway.
RV's aren't really airtight to begin with which helps to dissapate odors (and there is a bathroom fan--which is really easy to
upgrade to something 'more powerful' (Amazon) LOL).