Using a coupon with Apparel Item Options

I've got an item in my store (Double Hammock) setup as an apparel item and would like to offer a % off discount coupon with it. For this item, there is also the option to add an accessory (Hanging Kit) that isn't required but if chosen the cost of the accessory is added to the overall cost of the product. My problem is that any discount that I setup for the hammock is being applied to the total cost (including the optional accessories) and that's not what I'm looking to do. The accessories are separate products and I'm just making it easier for the customer by including them as an option instead of making them have to add it to the cart separately.   

Is there a way to create a coupon that only applies to the base product itself and not to any options that increase the cost of the item?

Thanks!