Pic 1 - With the retracts installed, lay a piece of tape on both sides of the wheel well. Lay a straightedge along the strut and draw a line on both piece of tape.

Pic 2 - Tape the door in place and lay another strip of tape along the strut line. Use the first two lines to transfer a line onto the piece of tape that is on the door.

Pic 3 - Place two nylon straps centerd on the line and mark the hole locations

Pic 4 - Drill the holes in the door

Pic 5 - extend the gear and bolt the straps to the door

Pic 6 - Voila!