OK, I had a thought about it:
Teensy must be turned 180 degrees and moved a bit towards the center (by a pad or so).
Then, 2 columns can be connected directly inside, 4 via the space on top and at least 4 through the space between row 3 and 2. It is possible to connect 2 columns through the bottom rows.
Row 3 and 2 are trivial, but row 1 and 0 should also be easy ...
OK, let's give it a try ...
