Reply to "What sort of tool cuts bondo like this?"

Here is what I ended up using.  It produced cutouts that the same as Kirk's.  I started with a 1 1/4  spade bit to start the circle.  I drilled a pilot hole from the rear of the car.  After the circle was cut I ground off the horns on the space bit allowing it to bottom out in the hole.  I had to shorten the bit to make clearance with fender when cutting the hole towards the outside of the car.