This is still a tricky one but I think I'm going to go with a diy pvc coast to coast with 3 drain points, ideally I would of liked a corner overflow but due to the bracing on the bottom it makes it a little difficult unless I use an acrylic panel cut to shap.
The nice thing with the pvc overflow is that it sits quite high,creates good surface Area, easy to desemble for cleaning and your cuts through the pvc act as a barrier so fish dont go down the pipes.