So your scenario is describing me in a month on my way to Disney, but I will have my husband there. My kids will be 2 1/2 and 5, and I will be 26 weeks into my pregnancy.
So we drive from NJ every year. We drive mainly overnight so they kids are asleep. I am not sure how far you are driving, but if by yourself and far you may want to do day driving.
So we usually pack 3 suitcases.... 1 for the adults (all our clothing and bathroom stuff), 1 for the kids (clothing, blankies, diapers if needed), and the last 1 is activities (pool toys/swimmies, coloring books, baby dolls, books, light spinners for the park, play little people etc). (The smaller things that can be used in the car on child's lap I split in half for car and hotel)
Oh and don't forget movies for the car!!
We also bring juice boxes and snacks.... we make sure these are available for the car ride, but we are sure to bring enough for the week at the parks too. You are allowed a soft cooler into the parks and we always go with plenty of snacks and drinks
We go to parks in the morning and leave them by 3 for the day OR we go after nap around 3 and stay for the night. This makes everything move at a slower pace for us. Especially by yourself I would aim for this type of scenario.
What else do you have questions about.... I tried to be general.