K, just bought some 3/4" foam insulation from the Depot, along with
some of that foil covered bubble wrap to insulate my garage door. It is
getting real hot hear in Dallas.

Now, I am stumped on how best to install this stuff. I would like to
attach the foil/bubble wrap to the foam then attach that to the garage
door with the bubble wrap facing outward towards the garage door.

Now the question is whether to install it "inside" the panels flush
against the door, or "inside" the panels but leaving about a 3/4" air
space, or installing "onto" the garage door, thereby leaving a 1.75"
air space.

Keep in mind the metal garage doors have cavities due to the bending of
the edges for reforcement. The cross section of the segments are sorta
shaped like a really big "C":

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It is my understanding the larger the air space between the door and
the bubble wrap the better. Can anyone confirm this for me?

Thanks.