At the 12 km mark, you will be halfway to Roncesvalles, at the 'Virgin of Orisson' monument. You can walk there on the first day, which will complete the steepest section of the stage to Roncesvalles. You will have ample time for taking a slow pace, lots of breaks and rest stops, plenty of time to gaze at and take in the scenery, and to enjoy a great day of walking. Then, you can take either the Express Bouricott shuttle back to either Orisson or to St Jean Pied de Port to spend the night.
The next morning, catch the shuttle back to the Virgen. Then walk about 8 km up a much gentler grade to the Col de Lepoeder, and another 3 - 4 km walking downhill from there into Roncesvalles.
You will need to make reservations for the shuttle ahead of time, but that is easy to do:
https://www.expressbourricot.com/contact-and-booking/
if you want to spend the night in Orisson, reservations are also a must. I would also make a reservation if you decide to go shuttle back into St Jean to spend the night.[/QUO
Lucky you No Fog No Mist No storms or Driving rain or Snow in Pyreenes. On one of my trips from SJPdP fog so bad we used a rope to stay together as visability down a few feet. On a good day its bit of heaven Buen Camino