I don't know enough about Buddy Club's design... but can you just wrap a chain wrench on the silver surface here (maybe with a thin towel to prevent damage), and tighten with an impact followed by a torque wrench?
If that doesn't work, can you lower the spring perch and move the spring down... then strap onto the shock shaft with a strap wrench or chain wrench (with padding)? Same process of impact + torque wrench.
