Don't use FP+ for Barnstormer. You should save your FP+ for attractions that you can't get FP-.
I have a DD5 and DS3 they both love Barnstormer. We will be arriving on 11/29. I have not set up and FP+ for Barnstormer even though we will ride it 10+ times on the trip.
Set up a FP+ for Tomorrowland Speedway (or something like that) for which you cannot get FP-and always has a long line. On your way to the Speedway grab a FP- for Winnie the Pooh. As you approach the Speedway have your runner go get FP- for Barnstormer and Dumbo.
Barnstormer and Dumbo are not connected to the main FP- system, so you can have FP- for both and grab another FP- at the same time. This is another reason not to FP+ Barnstormer.
At this point you will be holding FP- for Pooh, Barnstormer and Dumbo. Now ride Speedway.
When you are done with the Speedway make your way over to Barnstormer for your FP-. Then ride Dumbo with your FP-. Then ride Pooh with your FP-.
That's the ideal way to do that loop.