grahm,
It can go either way. The Aero units mount in just about any position. If you look at their site you will see the way they can be configured. They can come up through the bottom or from the side to accomodate the front clip sliding into the base. I believe the interest came from inadvertantly not latching the rear hatch and it poping open under speed. The Aero units can't be forgotten because you can't lock it without the key, and the latching mechqanism stands tall til it is shut. And if you did forget to lock it, it still would be latched.
I personally would like it for both. I am not building a period correct car and can buy many aero units for the price of a set of Hartwells.
Bill