This will get expensive.
First you will need a break out box of some sorts at the mixing station.
Then you will need some sort of encoder and transmitter.
Then at the apex you will need a receiver and decoder, to tell the apex breakout box what switches are closed
Might be easier and possibly cheaper to get a used apex and breakout box.
If you can run an ethernet cable from the mixing station to the apex, you can either connect individual wire pairs to floats and the breakout box.
Or they make usb ends you connect to, and you can put a modual and breakout bot at the mixing station.