first of all, welcome to AD enjoy ur stay
i had the excatlly same problem as what u had.. my employer's insurance only will cover 80% and i pay 20%.. however i struggle and struggle finding sources to help cover the 20% of my bill for the CI surgery. and find none.. and finally they offered me an form to fill out for income based (a special discount for peple who can't afford high care cost).. and i only had to pay $3,000 out of pocket i feel relieved that don't have to pay $20k.
i believe you can try that too.. if its an university