I probably should have leak-tested it in the garage, true, but it did work out! No trouble so far. *knocks on wood*
One strange thing that happened was that the silicone changed color over time - went from clear to a sort of mottled white translucence before it "cured" to the same look as the factory-sealed tanks I have, aka uniformly translucent. Gave me a bit of anxiety while it was happening, that's for sure! But since it DOES look the same as the other tanks' silicone, I don't think it's a sign of impending structural failure.