I don't have any suggestions but would love to hear what you end up with, Irulan, as I have a low-volume foot as well. I also have a rather narrow foot. Buying shoes is thus NOT one of my favorite activities, and mail order is out of the question unless it's a model I've used before. I have to try them on!
I will say that I've gone all over hot and sultry Belize, including long walks on city pavement, gravel roads, packed sand, and muddy jungle hikes in my trail runners (which just happen to be Vasque Blurs I got at REI several model years ago), and I never noticed my feet getting hot. My body and face, yes, but not my feet. I always wore lightweight and low-cut Swiftwick socks, which may have helped. They are amazing socks and wick like no other I've ever tried. So my feet never felt clammy at all.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow