I'm debating my wiring for the NPN-NC prox sensors for mine too atm.
Easier to wire in series, however I have a UCBB with 18 inputs.
That's 1 for the estop, 6 for the servo, which leaves another 11 available.

Will be using CAT7 solid core shield cable to go from control box to a connector box on side of machine using RJ45 shielding connectors.
RJ45 modules at either end.
Then from connector box on machine side to the switches using flexible cable.