My heart goes out to you. Having multiple people in the car, including a child, can extend the trip.
– Depending on the ability to synchronize bladders, I’d budget to stop every 3 hours for about 15 – 20 minutes. If it is just a bathroom break, use rest stops. They are easy to get in and out of quickly with plenty of space for the child to run around safely.
– CDs are great for sing-a-longs.
– Plan snacks in advance. We take a small cooler with sliced fruit, sandwiches, trail mix, bottled water or sodas, crackers and trail mix.
– Plan for car sickness. One very young niece would let it loose after 10 miles on the road. A good waterproof container, a roll of paper towels, wet wipes, and a change of clothes are handy.
– Are there any good travel games for a 3 year old? What about a DVD player for movies?
Good luck and safe travels!