I am also large but relatively well proportioned with my 280# distributed mostly centrally on my 6'5" frame. I just moved from Phoenix a few months ago, but while there I wore my 13 and 16 oz 8yd wool kilts in all kinds of temperatures and was never uncomfortable, hot or cool. Since moving to Kentucky we have encountered similar basic heat but added a lot of humidity, and am still wearing the 13 and 16 oz 8yd kilts with only a bit of sweating from the humidity. Wool is really both a good insulator and air conditioner, as well as shedding water in the rain due to its tight weave.

I just recently acquired a 16oz wool 6yd casual kilt as well as an 8yd PV for lighter duty use but have not yet found the necessity to wear either due to weather. Maybe later in the summer when the heat and humidity are combined.