I just accepted that as a newborn, a lot of #2's naps would be in the car seat. If the preschool run would be in the middle of a nap, I'd leave the house when naptime was supposed to start and run some errands first. Her naps would only be 30 min but I really had no choice. She survived. I made sure her afternoon naps were always at home in the crib and that's when I did all of her sleep training. It got a lot easier once she got a bit older and could handle more A time.
If you can find someone to carpool with, that would be ideal!