+1000I've yet to run across anyone working at a dealership that had enough suspension savy to properly tune suspension. Not saying there aren't a few out there but they are few and far between.
The first thing you need to do is set the sag. At 280 pounds you won't get the most desired numbers but you can make it better than stock settings. You cannot make the springs stiffer by turning knobs. The only way to transform the machine into happy mode with your weight is with heavier springs.
Do you have a Gen I or Gen II?
Youtube has plenty of videos of how to adjust a track winning suspension setup
If you want to PM me, I'll see if I can help you!