Perhaps a small sewage pumping station might be the solution? It's relatively expensive, granted, but they can pump 100m+ in certain cases.
Depends how badly you want the extra WC.
I'd say that any of the options on the table so far are destined to fail in what is likely to be a very unpleasant way.
Depends how badly you want the extra WC.
I'd say that any of the options on the table so far are destined to fail in what is likely to be a very unpleasant way.