Most tanks have a tempered bottom. The sides are ususally ok to drill. One of the guy in Sac drilled an AGA tank and it turned out that all the sides were tempered and the bottom was not. I think something mess up at the manufacture ..
polarized glasses, and sunlight are what you need. I forget the angle the sun needs to hit the glass, but test it with your car, since glass on a car is tempered, with polarized sunglasses you should see a checkered appearance. I'm fairly sure it needs to be a direct reflection from the sun, since I don't see a checkerboard when I drive from viewing the inside
Since your tank is small getting it out in direct sunlight after you figure out what angle the sun needs to more or less be at shouldn't be a problem.
If no one in the city does it, I may need to drive out to you then
Speaking of which - if I want this drill job professionally done, where can I look to go here in SF? And approximately how much will it run me?
If you are going to down here, DPV can do it for you professionally ;D. Not sure how much it will cost though. I don't know about SF area. Open a yellow book and call around. A lot of glass/windows/doors stores can drill hole.