Foster-based dog rescues?

My parents have been caring for a stray 6 month old lab/collie(?) mix puppy for almost a month, and they can’t get rid of him. All of the rescues & no-kill shelters they’ve contacted have been full. They’re in Huntsville, but at this point they’re willing to travel as far as Dallas to drop him off at a rescue.

They’re willing to foster him until he gets adopted. They’ve already started him on heart worm prevention, got him his first round of shots, and will get him neutered next week. He’s a fantastic, friendly puppy & Very Good Boy so they want him to get a good home, but they just don’t want a fourth permanent dog.

I would very much appreciate any leads on a rescue/no-kill shelter that can take him, or even give him a courtesy listing on their website.