First one is have the two tanks on one level connected by a pipe through drilled holes the second is have one tank above the other simply overflowing from top tank to bottom tank then overflowing into the sump.
You cant rely on 2 pumps to pump the exact same amount of water.
You cant do it like that because if pump 1 doesnt keep up with pump 4 your going to overflow the 5x2x2..
Give us a minute and ill draw up a few plans that will work...