We've tried and thought about a few things:
Has anybody had success impelmenting something like this in the past? Appreciate any help!
You could look into using Line Item Properties to help trigger the discount since those values can be read with Shopify Scripts.
Word of caution here hoever - it's not impossible for customers to add their own values when adding items to the cart. This means if you're adding the actual discount into the LIP, then it can be exploited.