OK, so you're not giving up your black gown and you're hot as blazes in your un-air-conditioned church? Wear the gown open. Wear it over street clothes: no stole, no collar, no bands, no hood. That way, if you begin to swoon you can shuck it unobtrusively. (I have a couple a time.) And demand a raise so you can get one in silk next time.
Oh, and I got a sale flier from Cokesbury. They have vesture on sale through June 30, including a bunch of Marshmallow Ghost gowns and some nice albs cut for women. Some nice stoles, but alas, no bands.