Hi Dan. First of all thank you so much for sharing your scholarship. You are a thoughtful and competent researcher. I do have a few questions and comments:

-where is a source that confirms that John was using a sunrise to sunrise calendar? I understand the Roman calendar started at midnight like ours. It seems in John 19:14 that John is using that calendar. Note that he puts Jesus in front of Pilate at the 6th hour. In Roman time that would be our 6am which does square with the other gospel writers using Jewish timing starting at sunrise for hours (not dates). Thus Mark refers to Jesus being crucified at the 3rd hour and dying at the 9th hour (9am and 3pm on our calendars). I think you believe Jesus was crucified at noon but Mark 15:25 specified it was the third hour. Darkness came at noon until 3pm (see Mark 15:33)

-You conclude that Jesus could not have eaten the Passover with his disciples, even though Matthew, Mark, and Luke specifically record that He did. I suggest that Paul, who we know was a Pharisee, was focusing on the sacrifice of the lamb. John also focuses on Jesus as lamb in both his gospel and the book of Revelation. (The lamb that was slain)

-I think there is a solution that involves two different calendars. At this point in history (and only this point) the ancient Sadducee calendar with slaughter at sundown until darkness (ie at the very start of the day) is being replaced by Pharisee dominated calendar of slaughter at the end of the day (3-6pm). Thus Jesus kept the Passover on one calendar and even was given up to Satan in the Garden at midnight when the angel of death struck Egypt. Then He was the Passover lamb the following afternoon according to the Pharisee calendar when He died at 3pm. Both calendars are in operation. The Jewish sources indicate that in ancient times the Passover meal was separate from the Unleaven Bread Feast. Yet the Pharisee calendar (which Orthodox Jews still use today) combine them into one great celebration on the evening of the 15th Nisan.

Regards, Hal B