Side visit to Pisa from Lucca

Your guide can advise you how to do this trip- it is super easy.

Train is regional so there is no need to purchase tickets in advance.
There is also a bus from Lucca to Pisa- which I believe drops you much closer to the Field of Miracles.

Just looking at itinerary for this tour- you really don't have much time to go to Pisa- maybe on that second day- after lunch. There is enough to see and do in Lucca though so be sure you allow time for Lucca.

Day 9: Tuscan Hill Towns and Lucca Today your guide and driver will
take us along the less-traveled scenic route through Tuscany, with
stops to wander through timeless hill towns with pristine views. Our
final destination today is the engaging and prosperous town of Lucca,
where, after an orientation, you'll be free to explore and find a
local trattoria for dinner. Moderate walking: 2–6 miles throughout the
day with some hills and stairs. Bus: 3 hours. Sleep in Lucca.

Day 10: Lovely Lucca and Olive Groves This morning a local guide will
introduce us to Lucca's elegant streets and historic churches, all
surrounded by some of Italy's most impressive Renaissance walls. Then
we'll head into the countryside to visit a traditional frantoio (olive
oil mill), where we'll learn about and sample Italy's famous
extra-virgin export and enjoy a farm lunch. The remainder of the day
is free back in Lucca to explore more of its layered history, or
perhaps take a walk or bike ride atop the walls. Moderate walking: 2–6
miles throughout the day with some hills and stairs. Bus: 1 hour.
Sleep in Lucca.

We did this tour a year ago, last October and I remember doing a city tour with guide then taking our tour bus into the countryside around Lucca to see an olive mill and have lunch and a talk on how olive oil is made. Time might be pretty tight for also going to Pisa but it’s probably possible if you’re comfortable coming back in the early evening.

If you decide to visit Pisa, you will want to prioritize the Field of Miracles. The closest train stop is Pisa S. Rossore, which is the stop before Pisa Centrale.