We're talking about flying into the smoke generated by a fire that can travel hundreds of miles with the wind and thousands of feet up.
Agreed in the case you have presented, the only query would be what the definition of "near" is, otherwise I would be happy to go, but the OP is stating if the reduction is not restricted to a specific area, you have to consider the entire area as being affected.
Like I said, on a moonless night, how do you know when you are flying into the smoke?
You can't do it with any cloud forecast below your LSAlt, so what's the difference?
Forecasts don't predict moonlight.
Aimpoint had a valid suggestion,
but if you can't see and avoid the areas of reduced vis, how can you possibly be flying legally?
CIVIL AVIATION REGULATIONS 1988 - REG 174
Determination of visibility for V.F.R. flights
(1) ** Flight visibility shall be determined by the pilot in command from the cockpit of the aircraft while in flight.
(3) ** Subject to regulation 257, the pilot in command of an aircraft operating under the Visual Flight Rules is responsible for determining the visibility for the take-off and landing of the aircraft.
(4) ** In determining visibility for the purposes of this regulation, the pilot in command shall take into account the
meteorological conditions, sunglare and any other condition that may limit his or her effective vision through his or her windscreen.