Hi! Relatively new frog owner here, I'm coming up on my 6 month anniversary with my little white's (dwight)! I'm seriously considering getting an American GTF next, but I have some questions first.

1. How loud is the green tree frogs croak? I've heard the videos and I don't think the sound would bother me, but I live with my parents, so I'm wondering whether you would be able to hear it in another room.
2. can you keep whites tree frogs and green tree frogs together **while they are the same size**? I know that No Species Mixing is a good rule of thumb, and I would never house differently sized frogs together, but I figured that since they are so closely related and their requirements are so similar, it could be conceivable? Would size still be a problem since GTFs are skinnier? I have an 18x18x36 for dwight, so I don't think space would be an issue.
3. Which is safer for Green tree frogs, paper towel substrate or Coir? When Dwight was a baby I used paper towels because he was such an aggressive eater, but is coir/peat ok for green tree frogs, or does it depend? I know paper towels have higher bacteria buildup.

If any of you have any thoughts, please let me know! Thanks