Mortgage REIT (mREIT) Financial Modeling

What is the best way for hands on practice with the debt side of modeling, particularly commercial RE debt? I recently purchased BIWS - they have a section on REITs but their financials differ from the debt side I'm looking for.

Has anybody had luck with this? Would the FIG modeling suffice (just taking external considerations of LTV, collateral)?

Thanks very much in advance for the considerations. I haven't seen a WSO thread on this so hoping it helps others in my position.