Answered by Shaykh Muhammad ibn Adam al-Kawthari
How would these times be used for fasting in Ramadan? It seems that any of the methodologies enumerated could result in 20+ hour fasts, which does not seem reasonable for an entire month of fasting.
In the name of Allah, Most Compassionate, Most Merciful,
As mentioned in an earlier post, one of the methods of calculating the times of Eisha and Fajr prayers respectively is the method of Aqrab al-Ayyam, which means to calculate the times according to the last day when Dawn did actually set in.
Now, for example, on the last day when true dawn (al-fajr al-sadiq) set in, it was around 1:20 A.M. This time will remain the beginning time for the fasts throughout the period where the sun fails to descend fully below the western horizon.
Indeed, the fasts may be twenty hours long, but this is something one will have to adhere to. It should be remembered that the duration of the fast on the last day when true dawn did actually appear, is also twenty hours, thus there is no alternative, but to follow this ruling.
One should always keep in mind that certain rulings may definitely be difficult to practice upon, but the rewards by Allah in the hereafter are immense.
And Allah knows best
Muhammad ibn Adam al-Kawthari