Our friend D Michael Thorn, long time Yes fan and fellow bassist, has got in touch sharing his memories of Turn of the Century being played live in 1977 :
” (…) Chris tuned his bass CADG. I saw them here Oct 8, 1977 on the GftO tour. I was in front of Chris at the stage barricade, so I was less than 3 meters from his pedals and mic stand. I remember watching him play this song where he would play the harmonic at the 12th fret of the E string, but it sounded a C. Also, noticed that he uses lots of upstrokes while playing this song, as opposed to the usual downstrokes. As for the pedals, I’m not sure if he recorded those or not, but live he would often use them and his effects in places that weren’t on the recordings.”
This is indeed great information. Not only Chris did use the Triumph bass to reach the high F sharp on the 23rd fret, as he also played the bass tuned in a low C, using the 12th fret harmonic to play the C I am playing on the 8th fret. I must say I did think about this possibility after watching the recent shows where Chris did use a low C on his Tobias extended range, but then I “decided” that it was something he came up with in the last 2 decades. With this information from D Michael Thorn, we find Chris using a low C back in 1977, which is only as adventurous as he’s always been… I have no idea how many bass players had made this kind of tuning back then!
So, my version, stays as “friendly” for standard tuning, but I will try to re-listen again the whole song to listen to that open low C. Of course the other passage which would suffer some changes are the octave leaps in E, in which now I would have to use the 4th fret of the E string, rather than the open string.
Thank you very much, Michael, for your insight on Chris’ playing!
Here’s D Michael Thorn’s Soundcloud page
Miguel Falcão (miguelbass) 
Thank you Miguel! ;-)