The law is the law , so a legal light IS required outside a special anchorage area..
Overkill IS legal, we use a 5 mile rated Perko Commercial fixture , although only 50 ft LOA , and only 2 mile is required.
The offshore cruisers in many areas find fishing fleets departing in the AM dark to be a problem, with or without a "legal" anchor light.
The solution is a dozen path walk lights tied around the boat.
These will last the night if the cheap installed battery is exchanged for a better quality quality , Radio Shack, or cheaper on line sourced.
Hard to pay $3.00 for a better batt on a light that only cost a buck, but cheaper than being run down!