I second jmarkb.
November will make it a race.
Check the daylight hours for your intended dates
https://www.sunrise-and-sunset.com/en/sun/united-kingdom/aviemore/2020/novemberYou'll be carrying lots of luggage and the schedule is quite unforgiving. Lot's of plans B are necessary, as any navigation mistake or some unexpected obstacle will make it impossible to complete your intended route. I wouldn't dare walking in darkness in the Cairngorms unless on the big paths in the valleys, even though I know the terrain by now.
In case you get caught by the sunset, the plateau side allows for camping, if the wind plays along (are you flexible with dates so that you can assume reasonable weather conditions?), on the MacDui side, it might be hard to find a suitable spot on your intended route.
I'd consider making it 3 days with a base camp in the valley or go for something more forgiving. Far away solitary hills (e.g. Ben Avon from Breamar) might be a great target for a November camp. The intended route is easier with 12 hours of daylight.