new WC?

[gusl]

I live in a 2BR apartment with one housemate, and I am tired of sharing a bathroom. The design is particularly bad because the toilet, sink and shower are all in the same space, ensuring that unless the housemates are willing to share that level of intimacy, it is impossible for one person to do X while the other does Y. (I try to have an open-door policy, but few housemates agree with that).

Amazingly for NYC, however, we have extra space in the apartment that nobody uses. In particular, there is a closet:

Length = 25in
Width = 28-30in

There is another closet of the same proportions adjacent to this one, in my bedroom. So if we broke that wall, we'd have a bigger space:

Length = 52in
Width = 28-30in


If we wanted to make a little WC (toilet + sink) the proper way, we would need to install new pipes, which would involve breaking the floor, and probably paying thousands of dollars to plumbers.

I am wondering if there is a cheaper solution, something like a portable toilet that fits in the 25in x 28-30in space... how easy would it be to clean it, and how often would I need to do it? Is there some sort of sewage pump that I could use from the portable toilet to the real toilet?