What are you going to use the 40gal tanks for exactly? Fuge, extra frag tank, something else, or you just plumbing them in to act as temporary sumps while you clean the actual ones?
This one is going to be used as a refugium. Not only that, it will add approximately another 20-30 gallons of water volume and be a breeding ground for mysis and other pods.
I still have to either get glass cut or get my acrylic guy to cut some baffles for me so the water level will sit specific and the common/drain chamber that will flow back into the main sump.