I live in Atlanta, and it's been known to get pretty darn hot around here, though not as much so as out west. With that heat in mind, let me say this: 16 ounce is fantastic stuff- that three extra oz. per yard really make a difference in the look and feel of the fabric.

My advice would be this: go for heavy weight fabric and low yardage! I have an eight yard knife pleater in 130z., and love it. That said, I have a low yardage (it's a kingussie pleater, but I'd suggest a box pleated kilt for you) kilt in 16 oz. tartan, which is cooler in the summer than the 13 oz. 8 yard! I kid you not! Much more comfortable, too.

Go for 16 oz. tartan and low yardage, brother. You'll love it, and it can often be more cost effective, as well, which is a big bonus.