I use 1 8-way hat for 360-degree view (with "forward" being mapped to forward_up), and I use a single button for "view up" -- so that way I get any direction with "any_direction+up"
Then I'd use the second hat for something else, like aileron and elevator trim, or for gear, brakes, flaps, or bomb bay doors, marking bombsite, bombsite calibration mode, or whatever (based on what MODE I'm programming)