My only critique on that would be the gap was cut a bit more than needed to allow glovebox clearance. Realistically it shouldn’t be an issue, the dash shouldn’t sag as it doesn’t attach to the knee bar.
Incidentally, if you wanted to go with the OE knee bars they can be had from DC Auto for $100 (support bracket for the passenger side still required, I believe).
The windshield defrost duct is a bear to remove. I recall not removing it from the car when I pulled the evaporator box.