I'm not familiar with your area at all, but last summer was the first time I took Lucas to my family's vacation home 8 hours away. If you are planning to do overnight, then I'm assuming you would be doing about 9 hours a day?
We took breaks every 2-3 hours and sat outside to eat when we ate so that he could be with us. Made sure he had access to water, even in the car, and lots of toys and chews. I think if you split it into 2 days you will be fine
Lucas slept most of the way and yours probably will too.