This wireless in this case means that the separate display only needs one wire, the parking light info 12V.

Does anyone have any idea where IN FRONT OF THE CAR I could get that info ? Of course, there`s always that possibility that we pull the wire all the way from the front to the back, and connect it to the parking light there. But.....easier way ? :(

If there's a switch at the gear lever to tell the car reverse has been selected that might work for you (I've never taken this apart, so I don't know). I presume by parking light you mean to connect the sensors to the reverse light so they only turn on when you're reversing. I'm not sure if the reverse light bulb is monitored for bulb failure, but you may get a bulb failure warning if you take extra power from there.

of course, reverse light was the one that I meant...

The reverse switch is normally on the gearbox. Unsure on the Skoda though.