You also have more options as far as wraps go with short dresses unless you have fur(s). It will, most likely, be pretty chilly up there so unless you have something warm and pretty to coverup with, coming and going, the extra length of a long dress will be mighty nice.
I do have a couple of nice coats, but nothing long. I also have a friend who has lots of nice accesories, jackets, etc. She’s offered to let me borrow whatever I need. That could help a lot.