If your toddler is like my son was, the heat of a summer trip might cause her BGs to run low. We wound up planning around the heat of the day and did not wind up getting a GAC (thank you Tour Guide Mike!). However, if we had not been able to do that, i would have picked one up to allow him to wait in the shade or a cooler area with an adult while the rest of us waited in line.
As I am sure you know well, toddlers' BGs can swing quite unexpectedly and widely. So you may need a different accommodation for your daughter than someone older might need.
Above all else, test, test and test some more. Have a great trip!