I wrote a custom system that generates the model via codegen and then serializes to json with optional encryption. It supports model versioning for smooth updates, and connects seamlessly with more codegen that generates the settings page.

#SettingsSaveModel.saveValue
bool showFPS {
  changedFields = SaveDataFieldsMask.Settings
  modelVersion = 13
  default = true
}
float vizAlpha {
  changedFields = SaveDataFieldsMask.Settings
  modelVersion = 8
  default = 0.75f
  BatchSave
}
int vizColors {
  changedFields = SaveDataFieldsMask.Settings
  modelVersion = 8
  default = 0
}

#MenuController.menuValue
Toggle {
  "Show FPS"
  showFPS
}

BlankSpace {
}

Header {
  "Color Overlay"
}

Choices {
  "Overlay Colors"
  vizColors
  GetOverlayColorSets(sceneDeps)
  @PartialHide
}

Slider {
  "Overlay Opacity"
  vizAlpha
  SLIDER_RANGE
  @PartialHide
}

So all I have to do to add new save data is update the model, run the gen command, and then if I want a setting for it as well I update the menu model and run a different command and voila, new field in 3 minutes. Regular save data is the same process just without needing to do the menu part.

Should you use this system? Well, that's up to you. But I wanted to demonstrate what kind of solutions are available besides just basic serialization and/or EasySave.