Options for Vacant Land in Spokane County

HI BiggerPockets,

I'd like to ask for some general wisdom from the group. My wife and I are looking to identify a wise use of about 3.5 acres of land. We are early 30's, no kids, living in WA State (Spokane area). 

Here's our situation:

· My wife and I are living essentially rent-free in a family-owned residence (1937 build, 2 bd 1 ba). In return, we are renovating the place.

· The property is free and clear

· We can likely be here for another 1.5 years in our current situation

· We are clearing $750 a month on our rental 10 minutes up the road. We have awesome tenants who will be in the home until at least July '23

· There is about 3.5 acres of vacant land on the property we're at now.

· My aunt/uncle live next door to us, and my mom lives next to them.

· Lastly, my family would actually like for us to buy the house and land from them. I believe it would be a reasonable deal (and my wife and I enjoy living there already).

Goals:

· Financial independence (of course)

· We would like to do something productive with the land rather than just have it sit vacant

   · Could we farm something on it?

     ·  Lease to someone?

   · Build a small apartment? Like an AirBnB?

         o There is something called a Detached Accessory Dwelling Unit where we may be able to build a small apartment. Can't be more than 2 bedrooms, must be 800 sq. feet or less, and must be 150 feet of the existing residence.

· A close family member had (years ago) inquired of the County of the possibility of building a traditional home in the vacant area, but was told "no" due to only being able to have 1 residence per 5 acres (county rule, I believe)

Question:

· What productive activity or step would BP recommend we look into with this vacant land?

Thanks a ton!

John