Affiliate for WooCommerce

I would like to have to option to pay commission based on the profit of the sale or select which fees reduce profit. For example:

Seller gets 20%

Product: $200
Merchant fees: -3% = $194
Cost of Good: -$30 = $164
Incentive Offer: -$20 = $144
Coupon to close: -$30 = $114

Profit is $114 so seller gets $22.80 rather than $40

This allows sales people to negotiate the sale without having to manually pull out coupons and gifts. While I can account for the product cost and merchant fees, I cant account for a discount or gift unless I put that gift into the system and give it a negative commission value.