Cape May,
A native guide here (actually a refugee from the east coast megopolis).
A decent (now) camp ground is the Wayne County Fairground. It is as close as you can get and even the FHU is not expensive. Just don't be there in early August as that is fair time. Break the rig there as parking at the museum is not good for RVs.
The Henry Ford Museum is good for a day just by itself. Get there at opening and wear comfortable shoes. It is 18 acres under one roof.
Greenfield Village is just as much, but watch the weather as it is a village and requires miles of open air. It is now scooter friendly.
Will a day do either? Yes, but you have to keep moving. I volunteered there and DW was a docent and we can still kill a day there with great ease at any time and when there is an event....
There may be other stops you should make. If you get back to me, I can rattle on a while and it might be worth your while. Just tell about other interests and I will shake some books.
You will be at least 12 road hours getting here, As we have not run that route in recent years, I cannot suggest a good place for a mid- travel break.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.