Is there any way to have auto stop work when the temperature is < 40F?

In the Insight there is a trick I use.

When it is that cold the car assumes it is more important for you to have cabin heat than to have auto shutoff. (Usually true.)

A way around this is to turn off the heat just as you arrive near the stoplight. This way the car thinks it is ok to go into autoshutoff mode. If you still want a little cabin heat when sitting at the light, go ahead and turn back on the heat. The fan will blow whatever remaining heat that was in the system for you. Of course if it is a long light, the remaining heat will get "used up" and then you will get cold air blown into the cabin.

It works ok for short stops. Or if you are hardy, just leave the heat off.