Elk keypad KP2 with PIN reader

You you can add an external 26 bit Weigand reader to the KP2. There is a pin header on the KP2 board for a flying lead connector that goes to the reader. Two pin flying lead connector is ordered separately.
I was trying to find the reference but was unable to do so. Is it possible to mount the prox reader behind this when using the flush mount kit?

I got my KP2 just havent looked at installing it yet as I have some notching to do. I was planning on adding prox readers, do I need to put something other than the keypad on the wall to do this (or can I install the prox reader within/behind the keypad)?
ELK sells a 26 bit Weigand Reader that will fit behind the KP2 with the flush mount kit. It works fine that way.