Okay, so I've been working on this setup off and on and I'm trying to decide whether to put the live planted area under the basking platform in the 90gal, or to put it in the 40gal. The 90gal is too deep for the light to adequately reach the plants at the bottom of the tank, so I was thinking of suspending a box/cage under the basking platform (made out of eggcrate material so the light shines through). That would free up some swimming area underneath, but it wouldn't look as nice. Here's a drawing...
The other option is to raise the height of the 40g so it's the same as the 90g, and then extend the basking platform over part of the 40g and then just run eggcrate from the end of the platform to the bottom of the tank so I can grow the plants in there...
The other good thing about the second design is that I have an XP3 for the 90gal which should be more than enough to keep the water clean. But I only have an Aquaclear and a Zoo Med Turtle filter on the 40gal so I think the live plants would help keep that tank clean.
Any suggestions, ideas, critiques?