Can anyone recommend the most helpful books on learning how to play a classical guitar as a beginner?

After teaching music for 37 years, yes, I can, It is called the phone book. You call the best teacher you can find. Do not whine about the time and the cost – if you intend to do this, and do it right – pick up the phone. The alternative is a huge waste of your time – you will take forever to become merely acceptable, if at all.