By "energy drop" are you referring to a blood sugar event or some other sort of fatigue? I don't golf very often because my attention span fails 12-14 holes into it and I generally don't enjoy the last few holes very much. It's happened often enough that I remember it and don't push for golfing events these days. I've only played a couple of times since I started pumping (2008) and haven't attributed it to BG problems as much as just the sort of tedious nature of golf, which I know many people enjoy a great deal.
Re snacking, if there's a bg drop that needs adjustment, I think that you may be better off treating it with fast acting carbs. When you're golfing, if you're walking, you're lugging your clubs around and hiking around looking for balls, etc. and is plenty of exercise to push your BG down. In many cases, fat/ protein will push your BG up over a longer period of time than you would need for quick adjustments. One advantage of golf is that you can pack quite a range of supplies into your bag, not to mention the beer vendors on the course!!
Re bars, I like Kind brand bars. They have a walnut/macadamia/ protein barthat's tasty and filling and 13G of carbs