Providing you are not insulin dependant then you really shouldn't have to worry about the exercise reducing your BG enough to cause a hypo. If exercise and LCHF is all you're using to control your diabetes then I wouldn't worry one bit. Likewise, there's no need for you to worry about hypers either, providing you're eating the right things (which you will be on LCHF).
If you were to test your BG pre-exercise, post exercise and every hour throughout then you'd get a good picture of what your BG's are doing, but I'd be surprised if you saw much of a change if any. You may see a small spike at the start as the body's natural response to exercise.
The reason diabetics tend to snack/take on extra carbs during exercise is to compensate for the increased sensitivity to their medication during exercise. Basically, when exercising - medication will typically cause BG to fall more than when not exercising.
As you are not taking medication you can feel free to snack as a non-diabetic would when doing this sort of exercise. Mainly to keep your energy levels up. Providing your liver is functioning as it should be you'll find that it'll do it's job keeping you going throughout the duration. Just make sure that if you are snacking, you're snacking on things that won't send your BG soaring!
Good luck!
Grant