Hey, it works! I started half way through the day and didn't submerge the cases or anything, I just brushed on some of this Retr0Bright misture, left it out in the sun for the afternoon, brushed a little extra on every now and then, and this is how it turned out:
Next time I want to use a plastic tub, start earlier and pay more attention to it during the day, but I'm still pretty pleased with the results!