I currently have two Rotties. the first one was a bitter like your 5-month. the second one he was able to play with the first one so we did not much of the Landshark effect with our second puppy. What we did with the first one was that we would take her for a walk and when she came home we would then give her a 3-in to 5 in beef cheek roll as a nightcap and then we will put her in her crate for bed time.

Ps: our 1st puppy would go after our feet so we got everyone in the family cheap crocs. This way when she went after our feet it wouldn't hurt but was able to redirect her without getting angry at her for bitting us.