I received a few Summer Comfort samples last year, thinking I'd buy big (60 meters).
The quality is BL139. My favorite was/is the solid gray. 250g, but the bulk is reminiscent of Crispaire, which is a no-go for the hottest, most humid days of summer. I can see why bench tailors love the stuff, but, again, for me it works better in May, June, and September.
There's Panache. Fox also makes a panama worthy of mention.
And, to borrow from an earlier post, if you're okay going the H&S route, there's Cool Breeze and Cape Horn Hightwist.
The awfulness that is a high temp-high humidity combo merits a more relaxed attitude toward the higher Supers stuff--and here I mean 110s and 120s. When it's that hot and sticky, fineness of fiber makes a difference.
An amendment of an earlier post: 7/8 oz. Fresco, not 6/7.