So it doesn't look so bad on camera, but the particle board is quite brittle and disintegrates with minimal handling and, I am interested in long term durability and being able to rock the cab back on it's edges without worrying about damage, which is why I don't want to just fill the corner on the opposite panel with bondo.
Another factor, I will be laminating over this, so I'm not to concerned with seams, as long as it's level.