I thought that was an option under the wii tab in settings
It is. I think Dolphin ignores the in-NAND setting, as AFAIK even if you have a real NAND dump, it HLE's the IOS file that reads it and uses Dolphin's setting.
Booting Wii Menu and changing sensor bar position/sensitivity is the same as changing these options directly in Dolphin's GUI. They're stored in SYSCONF, nothing related to IOS or NAND...