Thanks for the replies
Casting would be a great solution but not very practical for what we are able to do, most of the time we're in a field with our events vehicle so there isn't a screen for us to cast to.
I will look into Google Expeditions, I have been thinking about switching over to Cardboard at some of our events as I've heard that the Gear headset isn't as suitable for younger children. We're also organising a stargazing festival next year and we were thinking of giving away some headsets at our stand so that's another reason!