So you're cutting perpendicular to the slope from the bottom? Maybe try cutting at 45 degrees? That can't get a little weird as the crest the slope though since one front wheel gets there first and you can scalp. I lift the deck at that point. I don't run Scags though. But I'm still not sure I understand exactly what's happening for you. Rigid frame machines handle differently than ones with suspension. I suspect that's the issue. I'm assuming your Ferris has a suspension system.