1800 miles in 3 days with 3 kids in a truck. Crazy or not

I'm going to go with crazy. :B

Before the trip take the kids for a ride, at least 12 hours, and see how they hold up. Then tell they you want to do it for 3 days in a row.
That will give you an idea of what you will experience.
Don't forget, the first day may be fun and exciting. The next two days not so much.

On an 1800 mile trip, you will surely hit road construction, traffic jams, etc.. It will be 3 long days in the truck.