I agree, keep the enclosure humid but don't spray him. Wounds heal best when they are clean and dry.
I'm glad that he's hanging in there. You should be aware that there is a possibility of long term damage or even a sudden death at some point due to unseen damage to his organs. This doesn't mean giving up on him, but knowing that you're doing everything you can to heal him up but it might not be enough and that wouldn't be your fault!
I hope he heals up and don't sweat the scars. BPs are gangbusters at losing even horrific scars over time. Every time they shed, they lose a bit more of the scar until you won't be able to tell.