Getting the sweater lapels reversible with a cable motif as I had planned is beginning to seem daunting, but on reflection not all of the front panel will be turned back, just the portion across the neckline opening minus the overlapped button bands.
Per Shirley Paden, the neckline opening should be 40-50% of the back shoulder width, so, assuming a 2″ overlap for button bands, the maximum width of the front panel that needs to be reversible is:
separate button bands: ((16″ shoulder width x 0.5) / 2 fronts) – 1″ of button band = 3″ x 4.5 st = ~ 14 stitches
integrated button bands: ((16″ shoulder width x 0.5) / 2 fronts) + 1″ overlap = 5″ x 4.5 st = ~23 stitches
Fourteen to twenty-three stitches in reversible patterning is entirely manageable.