I'd use one of the 2 gallon bowls, leave out the salt because it's a stressor in and of itself (just keep the water very clean), add the stress coat, lots of silk plants to hide in and lay on, and let him have a few days of feeling safe to recover. :)
As for your divider, if you can't make it taller, I've taken a narrow strip of plastic wrap, let it hang down into the water on one side of the divider up against it, and pulled it taught across the top where the wrap now meets your cover/lid/hood, whatever you use as a jumping-out-preventative. They can't jump over that, because there's no-where to jump *to*.
He's a cute boy, I hope he's feeling better soon!