Garage doors lack insulation, but you can do something about that.
I live in South Florida, and while it doesn't get as hot as in Texas,
it does get hot. We added insulation to our metal garage door in the
form of Styrofoam insulating panels slipped into the inside of the door
ducktaped in place. Fiberglass insulation with the cardboard backing
would work as well. (Which has the better R value??). You might have
to re-balance the door after adding the insulation, but in our case
the garage door opener didn't seem to care and isn't straining. The
insulation lowered the temperature in the garage during the summer by
at least 10 degrees F.
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Normally this would be OT in this NG ,but mentioning styrofoam =
polystyrene , it is veeeeeeeeeeeeeeery flammable and if used in an
enclosed environment ,people inside would be in real trouble when a fire
broke out. Insulating material should be fireproof or at least flame
retardent while not emitting toxic/suffocating fumes.

Frank GM0CSZ / KN6WH