You could try something like this: https://www.youtube.com/watch?v=4rdkGUFzvfc . It burns your waste and you'll have to empty the ash tray every 2+ weeks. It's more expensive initially but is also much more convenient.
Not van friendly, but maybe tiny house friendly assuming you have full electricity hookup.
Of course as another YT commenter put it, this doesn't handle "grey water" - another element of tiny living that isn't ever discussed.