Ten gallons is still very large for such a little snake. An enclosure half that size would be the outer limit on size, unless it's utterly crammed with filler to take up the space - and then you'd never be able to find your snake under it all! Mine are in 16 quart enclosures, and for my little guy, about 150 grams now, I still have to clutter it up quite a bit for him to feel secure at all. My largest female, who weighed in at 644g last night (pooped yesterday, but still just ate, so she's not really that heavy) is in the same size enclosure, and still isn't comfortable without a secure hide to cram herself into.
Note - 16 quart = 4 gallons.