We're likely giving up on the one-PCB idea, because it looks like it'll be a lot cheaper to use multiple PCBs. On top of that, we're going to get 2oz copper on the PCBs and remove the soldermask from the high current traces, so we can cut 6 mil copper foil and lay that on top of the traces to help carry current. Most of the connections to the board are going to be made with screw terminals and either M6 or M8 bolts, then we'll take some litz wire and terminate it with ring terminals.