I don't think 100% SEP IRA will be excessive contribution because the Officer Comp can be reported as Schedule C income (this is newly acquired information through a training with a tax attorney), as long as we force a zero QBI deduction.  But her amended Schedule C income (Officer Comp) will be lower.  

The reason to elect S-Corp retrospectively is because it is allowed by the IRS to save SE/payroll taxes, as long as we report a reasonable officer comp.