Relationship between S and O: S-dimension* 64/48 (1.333) == O-dimension
S40/R20 curves are the equivalent of O53.33 (about O54). S54/R27 is the equivalent of O72.
The 5x12 S layout is the equivalent of 6'8" x 16' in O.
I have not constructed an O layout that large (nor any smaller scale.) My largest previous O layout was 6x12. I did have a larger G gauge layout in the side yard 19 years ago, long ago taken down.