As long as their other bills don't exceed the other 66%, that is all you are likely concerned with. 

(There are several ways to address it)They're concerned their client will ask them for more information about seller financing, but they don't understand it themselves and don't want to appear uneducated.For these reasons, most real estate investors prefer to avoid an intermediary and speak directly with the seller.

“They” aren’t as concerned about the profit, any income is a bonus and the tax write offs are an extra bonus (a bonus bonus if you want to call it that.). 

I have no experience with lots and new-builds, so I am making this post to get ahead of any "unknown unknowns" that may bite me in the rear.The key theme is that I'm open to comments, concerns, alternate suggestions and insights from those who have done something similar to my scenario.

Obviously the main concern is that I would want to refinance out of the HELOC as soon as possible.

If you were concerned about the owner's name, you should have handled that up front.

@Patti Robertson, I understand your concerns. 

With the poor inspection on top of my concerns with the cash flow, I decided to cancel and continue my search. 

One interesting find during the inspection of the "in law" suite was that no smoke detectors were installed in the furnished basement.That being said, this has me concerned about the potential quality of work that went into the rehab, and whether or not licensed contractors/personnel did the work?

For instance, how to value a storage facility, management concerns, risk mitigation, current market cap rates, etc.