I thought about this, and what might work is to use shorts or chamois containing undergarments (Terry, Nashbar) and use running tights over them. The fabric is lighter weight and they come in colors, so you could avoid heatstroke. They're on sale this time of year, I just got some really fancy Fila ones in the mens dept. at Marshalls for ten bucks. Blue and orange, our team colors, with mesh ventilation panels on the back of the knees. Maybe this would work for you? The choices of fabric are really varied, there's lots of running tights around. You could be covered and comfortable.
In the winter down here we go out in shorts and tights over, then take'em off when it gets warm, so I know the two layer thing works well.

missliz