Sorry for not replying, but I didn't get any notification, so I didn't know I had any replies :S
The reason for the 5 hour window is that it fits well with my work schedule. It's about 5 hours from I get home from work until I go to bed, and then I won't have to drag any food to the office.
I've been doing RFL for a while now and have dropped ~11kg, mostly fat even though I've not been able to work out due to injuries. I've just restarted IF and it feels good to get some more fat in the diet, and even add some carbs.
August 18 is the date I've set to start working out again, and it will be interesting to see just how much brazilian ji jitsu my knees can take now, but the weight drop should make it a lot easier. On my training days I will probably have a larger eating window, mostly adding around 100g of carbs pre workout, and a carb+casein shake post.
My goal is to get down to 12-15% bf, and then work on my strength/size again.