First vacation with 15 month old - starting to panic lol

im a FTM to a 15 month old boy and we are going on our first vacation this weekend about 3 hours drive away. im starting to panic, hoping i can get some reassurance and tips/advice.

first- he hates the car seat. im scared he will just be crying and screaming the whole 3 hours. i can keep him at bay for a little bit with snacks but i cant give him snacks for 3 hours lol. im also scared he will crt and scream until he throws up and if we have nowhere to pullover what do we do?!

second- we want to leave early to beat traffic but we cant check in until 4. so i dont know what to do- how do we give him lunch, how will he nap?!

im okay about the rest of the trip becuse ill be with my whole family, but the to and from is giving me major anxiety. i try to tell myself “whats the worst that will happen” but its not really helping right now. im also worried somehow that he wont be okay from not napping and not eating lunch like our normal at-home routine. help lol