I suggest that you give us the option when building a coupon to have Thr!ve charge for any non-included toppings.
We have an offer that's 2 10 inch specialty pizzas for $25. But those pizzas range in price from $12.99 - $19.99! So if we do fixed price for each of $12.50 with max discount of $7.49 (to cover a $19.99 pizza) then if they order that $12.99 pizza, they can order $7 worth of toppings before getting charged! ... if only we could just tell it to charge for non-included toppings.
Thanks for the suggestion! We will be working on a new configuration tool for fractions in the near future and this is something we can keep in mind!
-Thr!ve Product Team