Today, they were measuring for their furniture and apparently are buying a different stove to use (we will put the current one in the garage which we aren't including).The reason I would be increasing the rent if the other people move in is due to market value, which doesn't seem to be discriminatory.

Were we off on measurements?

The only thing I'll add is a single project return or profit is not the right measure.  

My advise is for you set achievable goals, measurable milestones to get there and sight specific assets you want to go after. good luck in cornin’ and beyond! 

We just came back from taking measurements over there, and found that we've got a pretty much perfect spot for one, and a way to get it back there.

So you'll find a house that sells retail to an owner occupant for $50K next door to an REO that was sold in bulk for $7K, so the comps are not a good measure of value.The ones selling cheap need lots of rehab and the ones selling retail are in very good shape, so this is a city in major transition.

Is it off by a few feet in measurements or is it an entirely different property?

You would prefer the guarantor to own the place where they live and have great credit score (not the so-so scores you'll take from a tenant).The recentness  of the eviction helps in measuring the risk.

It's easier to measure than weighing a pet.

It would be difficult to measure anyway since it's not like an UP-DOWN-UP-DOWN, it's a gradual slope across the floor.