Hooking up a 3rd tank to the system

[Etaloche]

So I have a typical setup with a 45g DT above with a 20g sump on the bottom. I am running out of room for equipment and because of the way I have designed my sump without much foresight I am having troubles fitting a standard skimmer into my setup. I have some tanks lying around and was hoping to hook up a 3rd tank into my system but can't really come up with a nice way to do it. I was hoping someone might be able to help me come up with an idea as to how to go about this. I was hoping to maybe add a bigger DT and use the current DT as a display refugium which would give me more room in my sump for more equipment.