I have created a 3DPrint for the internal battery pack holder which contains a mount for MicroSD extension cable - no glue required:
https://www.printables.com/de/model/927961
A compatible bottom cover is available here, too:
https://www.printables.com/de/model/927962
Cool Design, going to print one. 
Is it possible to mount the SD little more in the back, or does it need Modifikation for this?
i want to keep the original cover.
Not with the default version, but I have uploaded a modified “_STOCK-Bottom-Plate.stl” one which allows the SDCard mount to slide in 3mm more (which leaves it standing out only 1mm).
With this it sould be possible to insert SDCard mount (even if you will need some helper like a needle-nose pliers to put the SDCard in) but keep the stock cover.
Please check - feedback appreciated 
