If it can be assumed that the bass gtr & L vocal will be centrally panned I advise this.
STEM 1
PT Left - (pan into centre on Neve) - Bass
PT Right - (pan into centre on Neve) - L vox
STEM 2
Mandolin
Fiddle
Dobro
STEM 3
Acoustic Guitar
Banjo
STEM 4
BGVs
Reverbs
This configuration reserves stems for stereo information and has important mono signals on their own outputs and desk channels.
So if you are using Neve channels 1-8, channels 1 & 2 will be panned centrally, down the middle or 'mono'
Dont forget to make good use of the Neve studios equipment
It would be a shame if you didn't use any cool stuff like reverbs, the Neve eq itself if required or other stuff only because you were obsessing about 'total recall'
You can recall stuff in the Neve studio with a pen and a pad of paper.
To come away from the session with your PT session saved + 4 sheets of A4 with sketches of outboard & fancy reverb parameters is perfectly 'normal'. The studio should assist you in this regard.