So the gabapentin got us through till 2:30am which is an improvement. I only got to spend half the night sleeping with her outside! LOL
I found that she was also a bit less frantic than the previous nights. As soon as I went outside, she laid next to me and fell asleep rapidly. I came back in the house around 6:30 and I thought she would follow me, but she curled up on the backdoor mat instead.
I think the gabapentin is helping a bit. Maybe it's wishful thinking, but yesterday evening she came in the house several times (which she hasn't done for over a week) and took many treats from Peter in a relatively calm manner.
This morning, she got another dose of gabapentin as we are hoping it helps with her general anxiety and will help long term with her training. (This is in addition to the setraline.)