[Ghostwhite]

Out of the four options I would use either 1 or 4.

Whichever way you chose I would definitely populate both input ports on the manifold, this will give your manifold better flow.

Also I would keep from running the compressors hooked to ports of the same tank if the ports are pointed direct at each other like the tank end cap ports do, I was told something along the lines of the compressor pulses would be fighting each other and causing extra strain on the system.