The US taxes global income which dramatically increases the reporting requirements.

However, you can get loans that are based on the performance of the rental and not your personal income and debt.

While that kind of income is not a deterring factor, when I looked over the terms of service many big red flags came up.

I like targeting outside of where I would live for SF and small MF (1-4 units) because of the lower entry price, usually higher cash flow since your rental income is higher relative to your debt service, and your appreciation potential is high if you can read the writing on the wall.

The house I will get is in a lower income area, currently worth $95-100k, and she still owes about $25k on it.

Could you put it on a CC and pay it off within the billing cycle with either your income or selling some stock if absolutely necessary?

You can Host Finacial revenue tool to get an average of the income.

I would like to build a duplex on it for long term rental income.

This is usually done to increase your rental income but it comes with a price as you are finding out.  

It is disheartening to witness a mentorship program that boasts substantial financial success, with students allegedly earning substantial monthly incomes, yet fails to ensure that their own employees receive even the minimum wage they are entitled to.