Meanwhile, 33-year-old Kopelani will join Northland after several years playing in France for Bourgoin and Grenoble.
The former Junior Kiwi switched to rugby union in 1998 and was picked up by Canterbury. He played for Canterbury and Wellington in the National Provincial Championship, and made his debut for the Crusaders in 2004. He also played for the Hurricanes before heading offshore. He also played for the Junior All Blacks in 2007.
"Tone will add more depth at hooker. We have Ross Wright but we want to create competition for places in the squad and we want the guys to put pressure one another," Ferris said.
The Northland wider training squad have been training all year, and Ferris said recently they re-established better standards within the squad.
"We're very, very happy with how the squad is progressing. We asked more of the players and they have all stepped up.
"We know there's a long way to go, we just have to make sure we are putting in the hard yards now."
Most of last year's ITM Cup team were training, with the exception of Jared Payne, who is playing for Ulster, and Tim Dow who has retired.
A 32-man squad will be named in early June, which will be cut down to 28 in time for the ITM Cup.