Day/night cricket of any sort is a big ask in September. This week we are as further away from midsummer's day than we are the last week in march, and would we seriously consider cricket then?
That's not to say September doesn't produce wonderful weather (cracking the pavements in Fleetwood today) but after 6 it goes chilly quickly more often than not, so add to the chill there's the dew and little evaportation.
It could be done with a drop-in wicket surrounded by astro - but which county will cover their ground with astroturf? Actually, that probably will happen one day!
Day/night Tests and CC games, June and July and very early August, and with good floodlights I don't think there would be a need for a pink/yellow ball, just play normally in whites.
Club sides play until 8.30pm and beyond in the middle of summer, without lights, so having them on and ending play when sun sets/dusk begins...can't really see a problem.
One option is Boycott's Law...play 4 day Tests beginning at 11.30am and finishing at 8.30pm. Long day for the players and more so the umpires (hey, there are three or four there, rotate them!) but Gillette Cup cricket started at 11am and finished well beyond 8pm often enough!