A group photo is indeed a good idea. We are going to take one between the holidays if things go well.
How's the holiday and group photo going? I am rather sure that your holiday is over and you've got the necessary proof of real person here. Honestly, it doesn't have to be leisure photo, a group photo in your own office is actually more convincing as it's not only show the people in your company, but also the physical evidence (i.e. the office room itself)