Birthday party problems?

Okay so I was planning on having my birthday party in Sedona. A hiking birthday party, then we'd go to this really cool creek. But then when I told my sis the idea, she said we weren't putting like 10 kids in the back of a truck and I could only invite 1 person. She thinks it's too dangerous having 10 kids in the back of a truck for 2 hours straight. So she wants me to take 1 person in the front of the truck But i wanna invite my best girlfriends and the guy I like so idk what to do! Is there any other way I can take more people to Sedona? Maybe take 2 cars? What should I do? Plz help, thxx