holy moley don't hang the OP on this one :)
It is the manufacture of the rv he has right now he is trying to deal with and he can handle the grey waste from his sink as he sees fit. (and the OP sounds smart and all and will do as needed obviously in this situation)!
OP call KZ customer service, your best bet. We had a 5th wheel with xyz problem and hubby finally just called customer service to the manufacturer and got a great guy that answered everything and we gained knowledge instead of guessing anymore.
Sometimes it is easiest to go to the best source and save your time vs. what we did on our problem and took forever to get 'no answer' from anyone til hubby just made that call and handled it all :)