Yeah. Like I said, pro micro is fine but you'll have to get creative with the matrix, wiring keys that are not physically in that row or column to be in another row or column. Making the matrix more square, so you can get it all on the promicro.
- Promicro is a clone of the teensy 2.0
- The teensy ++2.0 is different, uses a different processor, has more i/0 pins, but is fully supported in qmk, and usually your first choice for larger 75+ boards