Play Biting / Manners (1yo Hound Mix)

Just adopted a ~1yo hound mix last week, Thunder, maybe some Rhodesian Ridgeback in him. About 55 lbs, probably 10-15 lbs underweight.

Sweet boy, freshly neutered, little or no manners yet — neuter didn't go well to put it mildly and that saga's probably going to drag on a few weeks. May be exacerbated by his botched neuter and that I can't properly exercise him yet, but he's also up to 150mg 3x a day and still jazzed up much of time.

The good:

• He has name recall and comes back even if he wants to chase something.
• Highly motivated by treats.
• Religiously goes to his crate when I grab the food bowls to fill them up and knows to sit first even if he's not great at actually waiting for me to put it down completely. We're working on that.

The not-unexpected:

• Knows nothing else. No sit/stay/down/wait, and progress on those is slow because he just wants to kangaroo up in the air for treats.
• Some resource guarding, but only with full meals and doesn't exhibit aggression toward me. I just feed the boys separately and this is non-issue. Given he was starved to skin and bones, he's doing better than I'd expect. With treats, there are no issues whatsoever if my other dog is around.

The bad:

• A few dust-ups between him and my other dog (12yo Bassador). I've been bitten twice separating them. Thankfully, they seem to figuring each other out and are able to walk it off after a few minutes of separation.

The ugly:

• The play biting. Relentless. My arms are bruised and scratched up to my elbows. I look like a victim of domestic violence. He's fine when we're walking around but if I'm sitting down he belligerently wants my full attention and treats me like a human Kong toy. It's bad to the point I'm very close to returning him to the shelter. Just getting him back to the shelter this morning for an exam took about 25 min and several attempts to get in the car before I could distract him enough to get the car moving so he'd stop clamping onto my arm. Today's the worst it's been but I'll give him a pass considering he spent all day yesterday resting from his condition and didn't get breakfast this morning in anticipation of a surgery they're apparently going to punt on.

The environment:

• 2BR apartment. I am WFH so the 2nd bedroom is my home office. That's where his crate is but given his howling sometimes when he's crated and I'm in the same room, I'm thinking of moving his crate to my bedroom or living room.

Likely still on limited activity for couple weeks. Not optimistic on getting additional help from the shelter. They're supposedly giving me some contacts for possible behaviorists even though I previously had understood they had one on staff.

Desperately hoping for any solid wisdom on dealing with the play biting in the meanwhile. Everything else seems like solvable problems in comparison, but if this keeps up he's going back to the shelter. I will have no other choice.