How should I proceed if the terms will remain the same?

I am fairly confident Tatum McDaniel at Jacksboro National Bank said they can, but I believe she said 25% equity must remain.

If they fail to pay this option, then the option will be removed and they will remain as simple tenants.

It’s a great moment to explore what's out there, weigh options, and go for the best fit.For sellers, a slower pace might mean adjusting expectations, but the demand remains steady.

That is how I will limit the risk and remain flexible. 

You need to amass a large portfolio for it to be passive (aka hiring someone to manage).If you want to be financially independent as fast as you can then you need to do a few things. 1) get as high of an income as possible (this usually takes schooling and/or experience, think high income profession - law, medicine,etc)2) live as frugally as possible (you will sacrifice a lot here, think of not going out with friends, live at home/save on rent, etc)3) invest as much as possible and I mean invest not yoloing on random hot tips (you are starting young, time will be on your side)If you do this consistently and remain highly disciplined, you will get there faster than most.

One option is to have the buyer use a loan to buy out your existing mortgage, and then you can carry a second lien on the property for the remaining balance.

Given that the house is paid off but has $27K in back taxes, you could offer to cover those taxes upfront in exchange for favorable terms on the remaining balance—like low (or no) down payment, and small monthly payments.You could also negotiate for a subject-to deal where you take over the property subject to the taxes, while still securing control of the property for your BRRRR strategy.

So for the example above, the payment would remain the same until maturity but you'd also be paying interest on funds that you haven't used yet. 

However, if a unit remains vacant, I recommend setting rent just above the market average — in this case, around $1,800 as you've identified.