If you have different versions of the .wmb files like summer or winter then it gets difficult, yes. Entering a level from several different positions is easy though. First load the game or level, then set the player to the desired position.

The advantage of my solution over yours is that it is generic. Once you realised it is done you don't need to bother about the issue any more. Your approach will generate work for every level and almost every actor inside the game world.

The advantage of your method is of cause the plus on felxibility you gain.