What is the safest procedure when reversing out of a parking bay between two tall SUV vehicles with restricted side visibility?

1. Reverse briskly to claim the lane before any approaching vehicle reaches your bay
2. Sound the horn to announce yourself, then back out steadily without stopping again
3. Creep back very slowly, looking left and right for crossing pedestrians and traffic, until the rear window clears the obstruction
4. Rely on the parking sensors and reversing camera, which cover the ground the SUVs are blocking