The "take what you bring in" mind set is big with NASA. So just pumping it outside would be a no-no. In fact if you saw the Martian (or read the book)
bagging and tagging the poop is useful for NASA to see if there were any health issues with the Astronauts while off planet. Any toilet solutions need
to take that in mind when designing. like I said it's a lot more involved issue then just pooping into a hole.
Thanks for the luck, I'll need it given the competition so far.