Taking our first day trip! Advice welcome!

kris
Little man will be 4 weeks old when we go to my aunts house for Labor Day. She lives 2 hours away and we'll be grilling out. We'll be there from about 12-5/6. 
Any tips or advice are welcome since we've barely left the house since he's been born! 
FYI, I exclusively pump so we won't be breastfeeding but I plan to pump in the car and when we get there. 
What to pack??