Lots of context but very few details. If you are just looking for a broker please post in the Wanted Thread.
If you want help with the numbers, telling us you want to find a mass grave big enough to bury 10-11k in negative doesn’t give anyone much to go-on — what’s the mystery car? What’s the payoff? Details about the loan besides interest rate? What is ACV (what are buyers willing to pay, not KBB).
There have been a half dozen similar posts in the past 90 days (1-2 about Texas in the past month), search and read through those to see if it either answers any questions it generates more specific ones.