[aprssig] Suggestions for Automatic Power Off/Power On circuit for mobile rigs?

[Rich Mulvey]

Does anyone have any suggestions for an automatic power off circuit, for 
a mobile rig?

I'm installing my FT-8500 in my trunk, and would like to be able to have 
the rig power off after, say, 10 minutes, and power on when the car is 
started.

Having it power on is easy enough - I'm just going to insert a relay 
into the cigarette lighter line that energizes the power lines that I've 
passed conveniently next to it.  ;-)  But I'd also like the rig to have 
a delayed power off, so that it can get one last posit out.

I'd also like to have my GPS powered off, as well, since it draws about 
100ma, and I'd like to keep battery drain to an absolute minimum, 
especially when it's -30 degrees out.  Therefore, using the rig's 
built-in APO is possible, but that doesn't help me with the GPS.

I've seen the APO2 at http://www.aprsworld.com/apo/ , and I'll probably 
breadboard one up, but I'm interested in other solutions, as well.

- Rich