Host union Northland provide the rest of the support staff in Jed Smethurst (physio), Tim Hurst (strength and conditioning) and Conlin Locke (doctor).
Back said he was excited to get this "once in a lifetime opportunity" to be directly involved in a Lions tour, which only comes to these shores every 12 years.
"It will certainly be a career highlight, who knows what will happen in 12 years time.
"It's good to be part of the Baabaas set up too.
"I just got a phone call from Matt Sexton from NZRFU, who's part of the high performance set up.
"It was out of the blue, no application process or anything."
Back's credentials justify the decision as he served as manager of the New Zealand Heartland XV from 2009 to 2015 alongside multiple coaching staff, and is approaching his tenth season as Steelform Wanganui's manager, with the side being the most successful in the amateur Heartland Championship with five Meads Cup titles and one Lochore Cup victory.
"It's fantastic that from a Heartland point of view, it's not only players that can get recognised, but coaches and management." he said.
McMillan and his assistants will spend the next six weeks tracking players in the lead-up to the squad announcement in April, with the squad assembling in Whangarei one week before the match.
It is hoped Back's inclusion in the setup signals that Heartland-based players will be in consideration.
Back said the initial planning meeting has been held and while the focus is on Mitre 10 Cup players not contracted to Super Rugby, there should be at least one Heartland representative, as well as possibly even a club rugby player "as is the Baabaas way".
Formed in 1937, the NZ Barbarians are based on the original Barbarian FC club in Britain, where it is a tradition to include one club-level player for international fixtures.
The Barbarians will also wear a unique jersey for the game as their traditional scarlet red would clash with the Lions jumper.