Telenordia/Tortenmann germanium-gain pedals actually come with a warning that they will shut down temporarily if you leave them in bright sunlight for an extended time, resuming normal operation once they've cooled off. "How long" of a time or "how bright/hot" of a day, hard to say, it will vary widely. But as a rough guideline you might think if it's really hot out, don't bring the pedal at all; if it's moderately hot or bright, just try to keep the pedal out of the sun.
As to the best silicon fuzz, they are legion. Check out
BassFuzz.com or any of the 17,000,000,000 threads we have about fuzzes.

Most fuzzes are not germanium based.