if you can run the 200a sensors out through the wall into the meter box so you can clamp around the 400a lines before they split, maybe do that. i have dual 200a panels as well, and i think the highest combined load i’ve ever seen us use is about 60 or 70 amps when the hot tub is heating and all the minisplits are cranking out the cold air. unfortunately i can’t easily get into my meter panel without phoning up the utility to take off their tampering tag, so i’m just monitoring them separately
