OR...snazz it up a titch with a skirt. No sense in going formal. Again, this is in a barn.
Or you could always do my favorite standby of white top/cute skirt.
I also adore this dress, however, there is no way to guesstimate how long the legs of the iron dress stand are, and whether this would be a touch slutty or not. V. sad. Because I think it's fab and would be HAWT. Damn Paris!