It appears you can use FMinimalViewInfo::BlendViewInfo(...) and FMinimalViewInfo::AddWeightedViewInfo(...), defined in CameraStackTypes.h/.cpp to affect an FMinimalViewInfo struct.
However, it appears that a camera component does not have a variable of type FMinimalViewInfo, and the function GetCameraView(...) calculates the values that populate the pushed out struct on demand. Further, the struct does not have the OffCenterProjectionOffset variable set on it, so is unreliable.