I'm terrible for eating late. There are so many more interesting things to do than cook.I don't think 1 hour will make a huge difference in the effects of the fast, so go with the 15/9 and what works for your schedule. I struggle too with drinking enough water, but I have come to find not only does it help flush your system but it relieves hunger and helps with energy levels while fasting. If I don't drink enough water I feel terrible.
Oh and I don't think the time of day you eat matters as long as its not too close to bed. I am doing 8 am to 4 pm eating window, I don't think I could go till 10 am before eating breakfast, I'd rather be hungry in the evening than morning.
