They are available on some brands.  Like Gene, I feel they would be a problem.  You would be putting all of the garbage into your grey tank making it the same as a black tank with no way to properly flush it clean.  Residues would accumulate and in my opinion cause issue.  We try to keep as much food residue as possible out of the grey tank.

Waste King L-3300 Legend Series 3/4 HP Continuous Feed Operation Garbage Disposer is the modern best garbage disposal brand known to me so far. It has longest warranties in the industry. By following instructions , it is very easy to install , just follow the instructions. I personally suggest to have its experience at least once.

You could always carry a couple chickens (as they are lighter and more compact than goats or pigs.) You can then eat the chicken eggs, (think of chickens as waste recycling plants) and when they are done laying, hens are edible too.
Of course you still must dispose of the feathers, bones and such, but that's not very often.

If the CG says anything just tell them they are just morbidly obese parrots. Then turn the tables on the CG host or manager to deflect further criticism by chastising the manager for not being sensitive to your pet's weight disability.

Chip