Caravan for secret club meetings

Be at the secret meeting place in an hour...this is gonna be big! A friend from the stables has a birthday coming up and the caravan is the perfect place to plan an epic surprise party. If only we had a secret place to hide the invitations. Can you think of somewhere we could hide them? Let's all head to the rooftop deck to plan snacks and party games! Best. Headquarters. EVER!