Depending on your requirements and budget, another option may be a carriage house, garage apartment, or mother-in-law suite. 

As an example, the block where I just finished a giant househack/brrrr project - we bought the old dilapidated corner store building and converted it into a triplex and turned the old barn/garage into a carriage house.

MIL apts, ADUs, Casitas, Carriage houses,  etc are available and what I've had for 13 years. 

If you actually designate a part of the property to be investment only (a carriage house, Mother in law apt, or 2nd structure, then when you sell you will be able to take advantage of both the 121 and 1031 processes making your sale part tax free and part tax deferred.If you simply rent out part of the normal living space of a house you'll not get the benefit of depreciation. 

Lots of properties with mother in law suites and other accessory dwelling units called “carriage houses”.

The realtor believes the duplex might have been an original carriage house from way back when, so it has good history.

I'm too set in my ways now to want to share living space, but hopefully there are enough options with mother in laws, multifamily and carriage houses in the area.

I built a unit in the second floor of the carriage house (2000) that I moved into I. .  

There are a lot of older homes that will come up for sale in these areas and  if there is only a single family unit on the property then you can make value with a carriage house addition etc. 

NOIt looks good and runs for a little while but then what is lurking under the carriage and hood starts going bad.