It is our residence and the guest house would be at the rear of the property and we would like to rent it out or eventually move a parent in if needed.

There is a common floor and roof structure (rear porch/front porch and mechanical area for the A/C compressors) that connect the two units, allowing for the house to be one single building on the property.Your mountain house looks fantastic, just in the few photos you put up, I can see why its in the $195/ft2 range. 

Purchase price: $241,000 Cash invested: $15,000 From redfin-COMPLETE REHABBED NEW GARAGE BUILT BY DANLEY'S GORGEOUS KITCHENS WITH 42"ALL WOOD CABINETS WITH ALL SOFT CLOSING DRAWERS, NEW S/S APPLIANCES, NEW WINDOWS, NEW PLUMBING, NEW ELECTRIC/SERVICE, NEW BATHS, NEW FURNACES, NEW A/CS, NEW PRIVATE WOOD FENCES, NEW REAR SIDING, NEW TUCKPOINTING , TOO MUCH TO LIST COME SEE FOR YOUR SELF What made you interested in investing in this type of deal?

There is a small block building in the rear of the lot.  

The studio is 300 sq. ft. so very small but the rehab will include a rear Lanai extension adding +100 sq. ft for laundry and storage.

In the rear center of the building was a mechanical room accessed from outside by him only, between the two units.

A fenced (or hedged) rear yard is a must for privacy.A foosball, ping-pong, or pool table is a good feature to have. 

Hurdles:-See what the frontage requirements are, for rear lots and normal building lots.

I understand the position of @Marcus Auerbach but would premise that by the fact that every market in the country is different and as price points of RE are much higher in some areas, these standard % commissions fluctuate by location due to values and market conditions.

I purchased the property in July 2016 for $307,000, it consists of two units in the front and one unit in the rear.