I appreciate any ideas and input...I own a rental duplex that is doing well in the 4 years that I've had it. However, an old dirt access road behind the property was recently paved and has some new townhomes along it, leaving me with an interesting opportunity for additional cash flow. The lot is 60 ft wide and we could use about 30 ft of the existing yard without disturbing the tenants/leaving them with a backyard. The lot cannot be further subdivided nor can we add an ADU based on my conversations with the city.

My ideas: several garage bays to rent out, a paved or gravel parking lot with monthly fees (near a boat ramp), or storage units. 

Does anyone have any innovative strategies or success stories of their own turning unused portions of their investment properties or land into additional cash flow? Really appreciate your inputs!