Vacation

I'm 16 years old and my boyfriend is 18. He and his family have invited me to go on vacation with them this summer, as a part of his graduation gift. We've been together for 6 months now, and at the time of the trip, will have been together for 11 months. His family is fine with it and obviously there will be sleeping arrangements and such made, but how do I bring this up to my parents, who are super strict? How can I convince them that I should be allowed to go?