Something like this is too much for me at least. Cape May is an 11-12 hour drive from my house, and it's too much for me to do in a single day now, well, maybe with a friend for company. I used to do it on a lark, going on Friday, coming home on Sunday by myself with 2 dogs. Those days are gone. Enjoy your driving/saving money days while you can!
WDW is about an additional 3-5 hours than the Cape May trip would be.
Bobbi