I've gotten locking down the mirage drive in my outback down to a science. Here is how:
First I move forward so I am looking straight down at the drive opening. This involves me sitting on the 8" hatch. Then with the fins vertical I make sure that position 4 is on top as I look down. Then down she goes, and 99% of the time I have a good lock.
BTW you can visually confirm that the drive is down and locked. Although they are not easy to spot, when fully down and locked there are two chrome "lugs" or "tabs" that that extend and capture the pins on either side of the mirage drive. If you look down and do not see these "lugs" fully extended on both sides, your drive is not down and locked.
To make my "lugs" or "tabs" easier to see I painted the edges of mine red.
MirageDrive3 by
pgerhardt62, on Flickr