I'm working on several simplified, but further advanced designs, at the moment. One will use a triple chamber system and blender parts, like I've tried suggesting.
a 30 gallon capacity will hold the feces and an equal amount of water, plus the approximate equal volume of toilet paper pretreated with urine, for 4 people, for 6 weeks, with room to spare. That doesn't cover all the food waste, or much of the urine, but most of the urine can be used diluted as fertilizer, and for other products.
My initial design for the digester will be self-made using pvc sheet, various pvc pipe fittings, and blender parts. I'll use an RV flapper-valve type toilet, to minimize water usage. It'll be followed bu a 30 gallon barrel converted to aerobics, then discharged into an aboveground transpiration/grow-bed, for a zero-discharge system. Excess urine will be handled separately.