He's lucky you're the one who found him! Skin is remarkably stretchy stuff, your vet might be able to free up enough to stitch at least part of that wound if the skin flap is healthy. (Kudos on the willingness to provide veterinary care, BTW, Steve... I've noticed you mentioning going to the vet a lot. I think it's only fair if you're going to take an animal into your care that it gets medical attention when needed.)

In case you're taking suggestions, I'd be awfully tempted to name him Tang with that electric orange coloring!