Road trips with siblings?

my mom is taking me to Astoria Oregon to see a sunken ship and a world war 2 fort. That part sounds amazing the only problem is I live Cottage Grove which is very far away from Astoria. I have a twin brother who annoys me because well he has an eating disorder so my mom constantly has to check on him making sure he is eating and keeping it down. Then I have a 8 year old brother who constantly asks What if? questions and is really loud. Finally my little sister who is 5 insists on bringing her LeapPad learning system thing that is loud and annoying. Im going to be driving for 8 hours with these people. Any tips so I don't get driven crazy. I am planning on bringing my iPod but the battery sucks and will most likely die within the first two hours