@T.Albers, thanks for the descriptions and photos.
I've ordered the pen you referenced previously; however, I've had zero luck on line trying to find the HobbyLite Filler--well, I actually found one vendor who wanted $6.99 to ship the 8 oz., $4.99 item. I struggle with some of the shipping charges.
As Hancock52 mentioned the use of a wood block to support the backside of the work side of the car, have you tried this? I ask because I would be concerned with the aluminum tending to flex under the pressure of the pilot hole and/or Dremel cutting tools.