The bulkheads in the top go to your moflows correct? Did you detail how those are put together somewhere?
I pick up some 9 watt refugium ATS stand lights they are 3-3watt Bridgelux and is only 2" x 2" wide. They were perfect for what I needed since they are going between two pipes.
Also, where did you find these? I keep trying to figure out how to DIY some fuge/ ATS lights but the cost is always ridiculous.