Looking at it I take it that the sections are all fixed in place with any way of seperating the individual enclosures?
Could you put a vent on each face of each viv above the height of the ceramic so you get airflow above the ceramic? Would there be enough height in each section to put a false ceiling in each viv below the vents? Something like 6mm mdf. Any heat that is not going down into the viv would get carried out of the vents.
Just trying to think of a way of getting the airgap. Where the metal braces are between the vivs on my stack it's just fresh air which seems to provide the buffer.