The folks are flying. 

Thanks folks.

Many folks will say it is all about numbers and nothing else. 

I'd certainly run whatever I was planning on doing by my loan officer before I did it, just looking for how folks generally handle this. 

Over the long term, the rate difference will be immaterial because you have locked in a very low interest rate and can always refinance later if rates dip lower enough to justify the cost.I encourage folks to look for ways to invest without debt (equity partners, lease options, etc), but if you're going to get a loan, go for long-term, fixed rate. 

Most folks like Quickbooks but a PM software may also be a good fit for you - just make sure it's reasonably priced. 

I have helped folks with owner financed transactions before, but never have assisted someone where they paid it off so quickly. 

I had read/heard so many stories about folks who had done exactly this over the years and my goal was to do the same.

@Julian Romo you should come to the next REI Central event and meet some folks there.

For house hacking or renting this could potentially be a disaster; the code enforcement folks could ask you to remove un permitted additions.