You need to be more specific about the back injury. Is this a chronic issue? Or did the golfer injure their back recently in an accident, etc.? Before any strength training can begin, the back issue needs to be addressed. If you have more for me to go on, i.e. has he been cleared to exercise, do you have the KSAs to assess a possible root cause of the pain, do have any experience with back pain, function, and resistance training?
You may need to refer this person to someone more appropriate to work with them first.