OK, now this is odd...
In order to avoid taking my interior apart repeatedly and having to work in the cramped, and stultifyingly hot, confines of the car I connected my existing circuit to a different lamp and momentary switch and used jumpers to power it with my truck battery.
This is the odd part: Some of the time when I power it up with the hot lead to the positive terminal of the battery, the circuit comes up latched and the light is on. Other times it comes up with the light off, like I want it. Either way it comes up at power on, the momentary toggles it consistently. I'm not sure what the ramifications are for using the circuit in the car where power is supplied by the ignition switch... I imagine the ignition switch provides a more consistent power on/power off than jamming a alligator clip onto the positive terminal of the battery... Maybe I could connect the power lead of the circuit to the keyed hot with a spade connector and plug/unplug it until the circuit comes up unlatched then hope the key turning it on and off consistently brings it up unlatched...
Someone on the car forum where I got the circuit is working on an IC controlled circuit to do the same thing... Maybe I should just wait for that to be available. Still, if it's too expensive, a simple, but reliable, circuit I could put together might be preferable...
Someone who seems to enjoy teasing me with cryptic suggestions sent me this, but refuses to elaborate:
"A simple latching relay, capacitor, and diode will do the same job as that perf-board circuit . "
Any suggestions on how to arrange the components mentioned?