The SAM financial structures only show debt at the project level. The tax investor (lessor) in the sale-leaseback model may have debt, but at the corporate level.
To consider a tax investor with debt, you could use a weighted average cost of capital (WACC) as the required return on equity (RROE), or IRR target on the Financing page, where
WACC = (Debt Fraction * Cost of Debt * (1- tax rate)) + ((1-Debt Fraction) * RROE)