I never trust the online seat maps for finding loads for a flight. It only shows which seats are reserved, not how many tickets have been sold. One thing I do when I'm jumpseating on other airlines is I'll call their reservations number and list myself over the phone for the jumpseat. Each time I've done that, I ask them how full the flight is looking and they've always told me how many seats are available and how many non-revs are listed...or at the very least how good of a chance they think I have of getting on the flight. All you have to do is ask.