GarryS had a great question about how to do black water tanks, which are not my favorite....
((( unless your hooked up at an RV Park )))
BUT... I found this new info that was really cool for trailer toilets
http://www.google.com/search?q=loveable+loo&client=safari&rls=en&prmd=ivns&source=lnms&tbm=isch&sa=X&ved=0CAUQ_AVqFQoTCKqd1aCkjccCFcaSDQodYjAP8Q
or
http://www.littlehouse.co/2012/09/diy-compost-toilet-installation-part-1/
you tube video
https://youtu.be/IPpMLa1cc8o
or his story
http://www.littlehouse.co/2012/09/diy-compost-toilet-installation-part-1/#lightbox/10/
or a wall hung waterless unit
http://www.littlehouse.co/shop/gudloo-waterless-urinal/
I built my own box & I installed a bilge blower fan, a little loud, but ZERO SMELL when i drop a bomb in the pot.....
I would be using 20 gallons a day on black water & you gotta pay to dump that crap to boot.