Of course you have to decide for yourself, but I think that with this method it will be very difficult to lose that much weight in such a short period of time. Many people that have weight to lose have a problem with metabolizing carbs and eating only fruit will not do any good there. If you eat that much fruit, there will still be glycogen stored in your body during the day that you water fast, and the body always uses the glycogen before it starts to burn the fat.
I sometimes do short apple fasts or orange juice fasts etc. for health reasons and they don’t make me lose any weight at all. I’m not overweight, but I could lose a couple of pounds, and eating fruit for me certainly isn’t the way to do that. Although maybe this works better if you have more weight to lose.
Also, concerning your other question about driving: I never had problems with that while water fasting. In fact, after the first days, where you may get a headache, your mind is a lot clearer than when eating normally. Also, while Water Fasting
you usually have a lot of energy. Although I have never tried working out for 4 hours a day, I have often walked 20 miles a day or more while water fasting.
I know it's not too popular here on Curezone, but have you considered a low carb approach? (with lots of vegetables!) Eating 3 days of vegetables and 1 day of Water Fasting
would also make you lose a lot more weight. Anyway, be careful not to overdo the fruit, as this may give you problems with your blood sugar, which is not a good thing while driving either.