Thanks for your effort to respond qbteachmp. The presumption of profit you mention I believe refers to  IRC §183. I also thought that held the answer. Unfortunately this is a residential unit so it is subject to subject to IRC §280A. While this is often thought of in reference to family members the code specifically applies "to any individual  (other than an employee with respect to whose use section 119 applies) to whom the property is rented for a rental under the facts and circumstances, is fair rental."

While fair market rents are not explicitly defined Publication 527 provides:

"A fair rental price for your property generally is the amount of rent that a person who is not related to you would be willing to pay. The rent you charge is not a fair rental price if it is substantially less than the rents charged for other properties that are similar to your property in your area."

Regrettably in this case the properties were well maintained and despite meeting the presumption of profit of 183 would seem not to meet the fair rental 2(C) Provision of 280. For anyone interested in the painful history and how a below fair market rental becomes classified as personal use here is a valuable resource: ALR Section 280A Discussion and Overview 

Really good thoughts and suggestions. Thanks