Honestly, I don't think you're going to find something commercially to meet your needs. I had a commercial composting toilet, and it was truly awful. It used electricity. It STUNK. It was noisy. It needed cleanout every week or so, even though the manufacturer said otherwise. There were two adults and six kids at that point.
We finally switched to a sawdust toilet system, and are much happier. Google Jenkin's "Humanure Handbook." I think it's available to read online, so you don't actually have to purchase it. We have three buckets set up right now. One is inside (our indoor bathroom), sitting in a wooden box, with a regular toilet seat. Another is out in our barn, in the "outhouse"...it is a 5 gallon bucket with a snap-on seat. I also have the same setup in our bedroom for middle-of-the night pees.
I have several different composting methods, depending on the season! :)
We have two adults and five kids here now. Good luck! :)