Here you can see where the guys at Autopower go through the carpet and bolt through the floor. Their cut was nice and clean. They jam nutted the nuts on the outside, up against the plate they bolt through.
Above is the incision they made in the rear seating compartment. It doesn't look all that presentable, but once the padding went on, you cannot even see the hole.
Here is the roll bar in the car before installing the Simpson harnesses.
And from the other side...
Once the Simpson harnesses are in, and the bar has been covered in the padding, it looks much cleaner.
The padding will eventually be covered in a stock "leather" material with heavy duty zippers holding it on. It should look almost like a stock piece.
Here is the finished product.