Alterntive for Sealand 510

[AlaskaAlfie]

Are there alternatives to the Sealand 510 toilet for ultra-low flush applications?  The problem we've run into is odors. Basically any build-up of debris or minerals at the toilet flaps allows the water-trap to drain away. The super stinky odors from the holding tank beneath the toilet come back up into the bathroom .... especially when wind doesn't allow the odors an escape route up the vent-pipe. It n be pretty nasty.