When you go to sell, only investors will look to purchase it.  

Are you planning to sell your primary in the near future?

(If you work at a lower rate and sell the house, bit they don't you make more then them right?) 

Utilize PropStream or BatchLeads to identify cash transactions and skip trace the buyers involved.

Lastly, launching a CRE brokerage type platform that charges no fees to sell a property. 

I have some land in the Phoenix metro and am considering building 4 units to sell.

Plus they seem hard to sell further down the line because they have such a small buyer pool.Finding a good local property manager could be a solution, but I wouldn't know where to start with that. 

Sometimes its smarter to sell due to the tax benefits our country provides (stepped up basis).

So, you  each have the option of taking debt, adding your own cash, or doing a partial exchange and purchase less than you sell (and pay tax on the difference).The guarantor of the mortgage really doesn't matter. 

Alternatively, if your going to be buying real estate, consider selling and trying to close early in the year, that way you can have the entire year to get properties and do cost segregation that can offset that gain.