I'm somehow disappointed as there is no answer from tech support to clearly stated question;
From the documentation (Extension module template) the connector used is:
8526-4500PL
https://www.digikey.be/product-detail/e ... ND/1306250
It is obvious that this connector is too short (10.8mm) if RP is mounted in aluminium enclosure.
I would like to create my own RP extension that needs to go with aluminium enclosure.
Not answering to questions like this, gves bad reputation to the whole concept.
Regarding support on this forum I need to give a big "Thank you" to Pavel Demin. Without his (instant) help I could just throw my RP back in the drawer. For me, he solved basic things to use RP in a real world project but his work goes far beyond that. I'm studying some "examples" line by line.