Some care are must be exercised when quoting US FAR's re night VFR.
Part 91 applies to Non-Air Taxi Operations and Part 135 applies to Air Taxi Operations.
The Surface Light Reference applies to Paert 135 .
VFR weather Minima are visibility and ceiling....with Clear of Cloud applying to Rotocraft in uncontrolled airspace.
That there is no visible horizon or surface light reference does not enter into determining VFR.
Under the FAR's one can be in a situation where you are VFR but must control the aircraft solely by reference to instruments (Part 91).
Until a Victim is aboard the aircraft it may be operated Part 91 rather than Part 135......as many HEMEs Operator did for years......with dozens of fatal crashes to prove it.