Tho I am still a "wannabe" in the C-dory realm, my potty progression in RVs went something like this:
Bucket & Chuckit; VW van, 20mpg
Real portapotty; Alaskan camper on F250, 10mpg
Real (RV) toilet; Bigfoot RV, 7.5mpg.
YMMV, but it seems like "civilized" biology management comes with...