That
should totally work if done right. I myself keep wondering why folks who already have fish tanks don't just remove the lid and put in a floating raft with 2" pots on top. The fish like living in darker conditions anyways. If the tank were placed somewhere sunny it would need some covering on the sunny sides to keep algae back.
Also, I would recommend getting one of the bubbler tubes that attaches to a raised screen that sits under all of the gravel in the fish tank!!! As the bubbles rise in the tube they create water flow that can be aimed to create a current/water movement in the tank (which is both good for the fish and the
root zones). Entirely eliminating the need for a water pump/filter since the oxygenated water will be slowly pulled down through the gravel and provide the perfect environment for those nitrifying bacteria. Making the fish waste more bio available for the plants... and not as harmful for the fish.
Without this oxygenated environment the gravel will become anaerobic. The anaerobic bacteria will actually turn the ready made bio-nutrients back into their original state. Which is not as much food for the plants and is also toxic to the fish.
There are plenty of aquaponics folks who have a full blown aquaponics system... and use the water from their system to water either
trees... their garden... or wicking beds. I recommend looking up wicking beds since they are as water wise as aquaponics and are essentially chinampas with a modern day tech. twist. The tech. being just drainage pipe run under the bed and a water liner to keep water and nutrients from leaching away from the sub-soil. The drainage pipe acts as both a water reservoir and a way too aerate the soil. So you have to leave room for air in there.
Marty