I got 1 out.

Leaving the fogs on can cause them to blow? Lol wtf?!

Only thing that I've noticed speeds up the light blowing process for the rears are subs :P. I went through turn signal bulbs every 2-3 month in the Grand Marquis after I put the system in. When I put my new system in the bonne, I've only blown one bulb so far, and probably not bass related

Both of mine were burnt out when i got the car but i just replaced them about a month back.

I had 1 go out, replaced it. Then the other side went, replaced it. And now 4 months later the 1st one I changed is out again.

I replaced the drivers side rear marker light 2 weeks ago.

seems a bit excessive. I'm trying to figure out whats causing it.

92-99 use the same bulbs but they dont burn out nearly as fast.

Aren't bulbs burning out other than with some years of age a sign of spikes in the electrical system? from the alternator? from the battery connections? I do know in cold weather the alternator charges at a much higher voltage based on the temperature that the regulator senses and that can speed up bulb failure.

Are the woofers causing vibrations that make the filament of the rear lights break by shaking while they on and hot and soft?

None here, at 141,xxx miles. I've owned it for about a year now with no problems.