Deadlands Preparation II

Ok, so I have not yet cleared up all ideas, but the one I like most at the moment has lead me to another problem:
Do I try out novel concepts, like flashbacks and so on, or do I stick with a sequential plot?
I'd really like to open the game with a scene from later on in the adventure, but am uncertain about how it would work out.
The point is that flashbacks and so on work very well in long-running campaigns, I think, but can feel like overkill in a short adventure. Now, some of the characters that will appear in the game, have been around in the Weird West for some time so they are to all purposes long-running characters, which makes me incline towards using the flashbacks and time-jumps.

These narative devices also add to a more cinematic feel, which is exactly what I'm aiming at.
So the structure of the adventure will be something like this:
First day: Begin with a boom, perhaps a scene from later on in the narative, then roll back a bit and play the part where the heroes meet again and set out for some adventuring.
Second day: The heroes are now in the deep shit. Their plans from the first adventure have seemingly succeeded marvelously, but then something wicked their way comes... with a vengeance. The Day should end with anoter big boom.
Third day: Begin at the point where we began the first day, but now there follows not the flashback but the story continues from that point onwards. End with anoter big bang, the biggest bang possible, since it is the end of the adventure.

Things I need to watch out for are manifold. The largest issue I have, is the problem of consistency. If the adventure begins with a scene from very late in the narative, I need to have a way to lead the story to that point, no matter what the players do. This sounds a lot like railroading and in the purest sense of the word it is.
The trick will be to make it feel as if it was a natural development and not planned from the start. And possibly have a backup plan to explain the beginning, if the players manage to derail the adventure to an extend that makes it impossible to reach that particular scene.
I'll now try to fit my ideas into that frame and see how it turns out.