First of all, thank you so much in advance for your help and suggestions. My father was military and always taught me to be prepared, but seeing as I've never been in a car that long before and definitely not pregnant, I'm at a loss. I don't want to forget anything important either!
My husband and I are driving from Northwestern Oklahoma to his brother's in northeastern Ohio this Thursday. We will be stopping in Illinois to visit my family, so the most driving we will potentially do in one day is 10ish hours (according to Apple Maps, but my husband usually beats the time on there).
I am 25 weeks pregnant and will be 27 weeks pregnant on the return trip.
Unfortunately (is that awful of me to say?) we will be making the trip again for Thanksgiving.

I'm a FTM, so I'm forever grateful for the wisdom of you 2nd/3rd/etc time moms.
Thank you again!
ETA: it's 18 hours one way.
Re: Packing help! 18 hour (one way) car trip!
Definitely going for the comfort aspect over looking pretty! @ems0523 it wouldn't be beneficial to fly because of the multiple destinations (visiting my family in Illinois and his brother in Ohio). Husband and I both really enjoy roadtrips, so it wasn't really a question when we planned the trip (pre- BFP). For Thanksgiving's trip, I'll be in the third trimester and I think that the airlines have a restriction on flying then (I could be wrong on that though).