Traveling/ Packing, what are must haves?

I’ve read every travel blog and I still feel super overwhelmed about our trip next month from CA to TX. We fly out and then we drive back because we’re purchasing an suv out there. I’ve come up with a list of things to ship to my in-laws house like wipes, diapers, inflatable tub, playtex bottle liners and baby food. Can’t ship formula since we get Elecare delivered at home from insurance. Anything else I should purchase? We plan to take pack and play for him to sleep on. I wish I could take it all 😰 any travel tips or road trip tips are greatly appreciated