Hanging from the aitch bone is only of benefit when you don't have the height for hanging from the hock. Might be useful if you are going to hang larger deer but I don't see any benefit in your current situation as you have plenty of height for Roe. Packing them tighter will restrict air flow but that's only going to be an issue if you are putting warmer deer in with chilled ones and then chilling for longer periods. If you are happy to pack them tighter then alternate, hang some the by the hock and some by the aitch bone. That's what I normally do.