A road trip - how fun, especially with the pooch!!!
It's kind of hard to give tips, as I've heard many different dog-road-trip stories, and have found that every dog is different. For example, our Kate falls to sleep in the car as soon as we hit highway speed. She would sleep for hours! But when we're driving 60 km's or less (in town, etc.) she has her head out the window, enjoying the fresh air
Advice I would give is to stop about every 2 hrs or so for a pee break, also depends how much water Mack drinks. You've stated you have bones and toys for him - good, I'm guessing keeping him busy will keep him happy! We find that it was a lot more fun for Kate if we stopped at designated rest stops (as opposed to just the side of the road) for pee breaks. Especially in BC, where there's bound to be a lake at almost every stop! That way the dogs get a bit of fun while they're on their break, and it's safer for you and Mack too
Best of luck - I hope you have a fun trip and Mack enjoys himself too!!!