PBP is in 2018. My experience in long distance rides is that as long as you are a seasoned rider and ride long frequently that is all the practice you will need for PBP, LEL, or any other long ride. Time in the saddle is the most important requirement.
You might have a course that exactly mirrors the PBP, but on the day of the ride; cold, wet, tired, hungry, wind, crowd conditions with the mental stress of finishing thrown in, will all decide if you finish or not.