I ALWAYS save lots at 6am in the morning for reasons like this.
I have only recently started doing this. Before I just saved when I was tired of playing or after a major event (age transition ususally). I was thinking the Simpe idea would probably be the easiest way of doing this (rather then having to go into each household and have sims with a custom career find a new job) until you mentioned that some sims might still be at work...and you know, you're right. I have no idea which households my sims might be at work instead of at home.
I suppose I could use Simpe to track down which sims have custom careers and then enter those households, make sure they are home and either have them change careers in game or go back into Simpe after verifying their work situation.
It sure does seem like this "game" is a lot of work sometimes. Damn it all!