Let's also not forget another important point here...
Just because everyone is knocked unconscious (a Total Party Knockout as you put it) doesn't necessarily mean that everyone is dead.
If everyone is dropped to 0 HP... it does not mean that the monsters necessarily go around and coup de grace every PC right then and there. You (as DM) can see them all suffer a Total Party Knockout... but then have them wake up several hours later in chains in a cell somewhere if you want. Or tied up on a spit over a fire being built. Or strapped to an altar ready to be sacrificed. Or even right there where they all fell, waking up later to discover the monsters they were fighting are all dead around them for some reason. Or any kind of thing you can think of.
A TPK is an excuse for the DM to throw in new plot ideas forward in time if having everyone dead is not to their liking. You don't need them to reappear at a "checkpoint" backwards in time only to ask them to replay the story back up to where they had the TPK. Move the story forward. You and your players will have more fun with it I think.
Just because everyone is knocked unconscious (a Total Party Knockout as you put it) doesn't necessarily mean that everyone is dead.
If everyone is dropped to 0 HP... it does not mean that the monsters necessarily go around and coup de grace every PC right then and there. You (as DM) can see them all suffer a Total Party Knockout... but then have them wake up several hours later in chains in a cell somewhere if you want. Or tied up on a spit over a fire being built. Or strapped to an altar ready to be sacrificed. Or even right there where they all fell, waking up later to discover the monsters they were fighting are all dead around them for some reason. Or any kind of thing you can think of.
A TPK is an excuse for the DM to throw in new plot ideas forward in time if having everyone dead is not to their liking. You don't need them to reappear at a "checkpoint" backwards in time only to ask them to replay the story back up to where they had the TPK. Move the story forward. You and your players will have more fun with it I think.