So, my monthly payment on the underlying note is about $1,475 and I'm getting $2,400 for a cash flow of $925 a month.I apply the amount "down" to the agreed to option amount, if they exercise the option.

An exercise for you is to change this phrase "...knowing that my real concern is their inability to pay the rent due to maternity leave" and substitute "maternity leave" with "being X" where X is another protected class based on race, gender, ethnicity, etc.

I realize you've done this a lot, but what your advising people to do is to conceal material facts from me and my lending bretheren to induce us to make or not make decisions in favor of your client that might not be qualfied thereby weakening our portfolios.

They had pretty graphs and data, but instead they cashed out your 401k and spent the money on shake weight exercise devices.

Data migration is a costly exercise and many times very labor intensive. 

You may have answers to some of these questions already, but it is a good exercise to have some clarity on those goals, then you can forge the path to get there. 

And then when you sell the property if they exercise the option you could then 1031 the property.   

If you entered a contract to purchase without actually having the intent to purchase....then you may have committed fraud by the inducement. 

Legally, they may have the right to exercise the ""due on sale" clause, but I would review your mortgage, possible consult an attorney and/or your servicer to understand if they ever enforce this.Stepping back, putting title in an LLC may not provide as much protection as you think.  

Plenty of people will tell you lenders never exercise DOS.