white dresses at kohls Cocktail Formal Dresses Kohls Womens Plus
Description
This one is from Target and is super affordable

Choose something with a flowy skirt or lightweight pieces that will play in the wind loose sleeves to drape across your partners shoulders as you hug them tassels or beads or sequins that catch the light and reflect your surroundings
Its big enough to fit all of the essentials and then some but weighs nothing
You may want fabrics like jersey or velvet that will stretch a little, but are easy to wear