Sorry for putting on my naysayer hat, but I'm pretty sure that any such tank will not be entirely fuel proof. I think that at best you'd get severe yellowing, and there's a good chance that the thing would get brittle. I'm pretty sure that the "milk bottle plastic" look is inherent in HDPE, and that HDPE is what you need to hold fuel.
I'll be happy to be wrong -- you might want to find some clear plastic pill bottles and try them out, but don't announce joy to the world until one has held up for a few seasons.