Can one alter the 6th precept to accommodate one's family or daily routines?

My understanding of the 6th precept is that one should only eat between sunrise and noon. There's another question (What is the purpose of not eating after noon? ) about the purpose of it from monks' point of view. I would like to know about it from the laity's perspective. My questions are: 1. Is the purpose of this precept to practice discipline, to renounciate pleasures and so one can gain more certainty in their ability to be diligent? Is it so that one knows hunger and does not act on it? 2. if one is taking the 8 precepts, they should take all 8, right? There is no "pick and choose the most convenient"? This sounds silly when expressed, though I've read statements on Buddhism.SE and in books saying "don't do X if it would cause major conflicts in your life and you don't value X over the absence of conflict", be it child raising, vegetarianism while dependant on ones parents, meditating more at the expense of getting sufficient sleep, etc. 3. I still eat meat (and dinner) due to family pressures. Is it acceptable to make these allowances? My concrete example is that I often stay up very late when it is the days surrounding the New Moon, for Astronomical observation. (This is a date that many Thai laypeople commit to the precepts). So leading up to that day, I gradually stay up later and wake up later. Eventually, I am waking at noon. It is impractical and unhealthy at these days to be eating at sunrise, only to fall asleep, and then fast until I return to sleep the next day. Should I just fast for the same duration, shifted to healthier hours?