OP, you first stated that your final options were:
"To pay them to install a new engine or tow my truck off their property".
Then you mention waiting to see what your co-pay will be ... so, your truck is under warranty?
I'm just trying to understand.
Imo, if under warranty let them replace the engine and that should put you in a better position if you should decide to trade your truck off if your not satisfied. Your out some because of the "co-pay", but way better than something worth $2k sitting in your driveway as an static display ...idk.
The prices of used vehicles is down some. Dealers are not making crazy trading offers right now compared to just last year. Dealers are offering incentives on new vehicles, but aren't much.
Fwiw, if your truck is still overall still in good shape keep it and have the engine replaced, to (at whom evers expense), and you will have come out better, $ wise?