I like it!
Peeponics, with rabbits as the pee providers.
Easier to close the loop than with fish, rabbits eat most of the produce that we eat.
Diego Footer has a few videos on a clever wormcomposting device that does much the same thing.
The Worm Tap:
https://youtu.be/y5caoQ_EEuY
I wonder if the rabbits would be better off not directly over the sump tank.
The humidity might be bad for their lungs.
An flat plastic panel with low edges placed at a sharp angle under the rabbits would divert the urine and poo.
You could use a pump on a timer to recirculate water to the top of the diverter, cleaning the surface and aerating the water.