Rule 5 went out with the arc.
we're in the EU for another 7 months, so: SERA 5005 (F) (2) please☺
these are and should be the basics for a wannabee.
notice the 150m clearance provides a 'dome' around the aircraft.
should there be no "persons, vehicles, vessels, structures - one can fly as close to the ground as one wishes (outcas).
Not recommended for newbie's however until experienced.
In the cruise: COCISS and sufficient speed to avoid IIMC.