Buongiorno,
How late do you expect to be traveling? I am seeing trains that run at 8:10 pm and 9:10pm. What I do see however, is there are no direct trains (due to work they are doing on the train track) you need to change at least twice? That could be a bit of a bummer with kids in tow. I wonder if you might want to consider a NCC (driver with car) giving you both flexibility with your times and the comfort of being delivered directly to your Tuscany doorstep?
If you want, you can try sending a message via What's App to Simone, (+39 334 7053211) or Beppe (+39 392 140 0056) Both speak excellent English and can give you an estimate of how much it would cost.
Buon Viaggio,
Donna Denise