The camera has these small external heat sink plates which I might be able to add to, but it is a rough environment and I suspect that the problem will remain. The camera case is flat black which doesn't help much. However, the supercap is much smaller than the battery, and there should be no further swelling and distortion of the case now that I've switched it. I also tried running the AC in partial defrost mode, where AC air is blown up the windshield and across the camera, but it reduces the amount coming out the cabin-facing vents enough that it gets uncomfortable. It may be that I've got to replace the case every so often. Now that it's fall, I suppose I won't know until early summer whether that's the case.
In terms of access point collection, my observation to date is that my setup can get about 110 to 150 APs per mile of driving at the posted speed in suburban areas.So, 500k APs represents a lot of driving miles

! Since Phoenix is more or less an x-y gridded street plan, every square mile of residential area could produce perhaps 1k to 2k APs. There's a lot of square miles of residential areas around. Hospitals and the medical facilities immediately adjacent have the potential for 1k to 3k APs. There's a lot of hospitals here.
In my small neighborhood, which may be a bit more tech-rich than the usual, I estimate about 6 APs per household, based upon 119 residences. Nowadays, it seems every other iPhone or Android has its hotspot mode on. Also, more and more new cars are running full-time hotspots, which makes for interesting itinerant observation and MAC addresses that jump all over the map.
Downtown high rises are really interesting. Just parking at a spot and leaving Vistumbler running can produce thousands of APs over a period of several hours.
I'm traveling a bit as well, Minneapolis and San Francisco Bay area mostly, and just with the antenna in the laptop inside the car I get a lot of APs. If I came up with an easy external receiver solution, that would improve the efficiency more than double, I think.