Welcome to the forum!
Most ebikes are quite heavy, unfortunately. I rarely put mine on the car rack but when I do, I have to remove the battery and anything else I can to lighten the load and even then I have a hard time lifting it high enough.
Longer overnight trips with your ebike? What kind of range do you get on your bike? Remember that a loaded bike will use more power too. Do you expect to carry an extra battery with you? Charge overnight in a hotel/motel?
I'd love to do a bike tour through your wonderful wine country. SIGH