The circ pump would be electric. You're staying away from that though.
If you want to get away from black water, I've seen incinolets. They burn the waste. The one our rig had was propane fired iirc. Or diesel.
990SMT, 640A, TXC450, TE510, ATC350X, ATC200ES, 550MXC, BW200. Need more space in garage.