BBC shows it's currently around 13C in Atlanta so not super cold, I wouldn't be surprised if the fast idle drops back quite quickly in those temperatures so I'd just adjust so the fast idle hits the target from your service manual and see how it behaves when the temperature drops.
Do you suffer with the bike stalling easily or running rough when first started? Does the temp guage show bars really quickly?

For reference, My K7 Vee had an issue of the fast idle not kicking in at all and the bike would stall really easily for the first 10mins of every ride.
The fast idle now behaves as follows;
Kicks in every time I start the bike but usually drops back within 30 seconds or so on all but the coldest days.
The Vee has a more comprehensive table for fast idle behaviour in the manual so I followed these guidelines and I now get about 2k in winter and the revs drop back to 1,700 and then 1,500 as the bars on the temp guage appear. Normal hot idle after a few minutes riding.
I don't ride in sub zero so I've no idea what it does then

"only if they think it's tracker" OMG! I think you've 'let the cat out of the bag'.

I just really like taking a big bike off road it feels a bit naughty!
I am hoping to do more in spring summer

I wish I knew about some green lanes round where I live.

I am part of the TRF its a really handy way to find out "legal" lanes
Also means you can cross reference on YouTube to find out how bad or good they are!

@Frederick60, what do you hope to achieve in going the 16 tooth front sprocket route?
You have not provided any info on your riding style or the type of roads that you ride the most.

FWIW, my 1st gen K5 Wee has a 14F/47R sprocket combo, which is really great for slow manuvers, easy to pull off from a stop when in low moving traffic, better when riding in hilly country, feels more powerful when riding into strong head wind and much better when off the black top. The gear ratios are a bit quicker so one changes up quicker. When at highway speeds the rpm is slightly higher but then the Wee is not shy in running at higher rpms.
I did find that the fuel consumption seems to increase when riding above the 6,000 rpm for extended periods. Maybe your newer model is more forgiving.

My K6 Wee on the other hand has a 16F/45R sprocket combo for a more relaxed / lower rpm / less buzz ride at riding at highway speeds, but I find that I need to ride / slip the clutch when pulling off on most inclines, plus when riding in slow / busy traffic.  On the K6 I find that I seldom end up in 6th gear when in city traffic speed limits, as the rpms are sometimes too low for any useful pulling power when riding at the 60 km/h limits.