I now monitor the owner's equity, return on investment, and other factors and then proactively reach out when they are ripe for selling, exchanging, or adding doors.

Might it be smarter to offer a slightly lower monthly rent in exchange for a tenant who feels more content.

While I don’t suggest that the smaller type investor purchase and utilize “exotic” vehicles like foreign asset protection trusts, family limited partnerships with outside controls, or Byzantine or convoluted maze of ownership entities, the more simple strategies of using Series LLCs, self directed retirement plans, and paying off their home mortgage to the extent of the Federal BK homestead exemptions can insure that a plaintiff attorney never even considers going after them.  

Following this exchange, and after a few more callouts from Melanie, you appear to have downgraded your account on BiggerPockets, and gone inactive coming back only recently to respond to Melanie's post here. 

If no consideration is being exchanged, then all you would need is exempt stamps for State and county. 

.- If I use a 1031 Exchange, does the next property also have to be a duplex?

The "cash-for-equity" program from QuickLoans appears to be a shared-equity or deferred repayment model, where you receive upfront cash in exchange for giving up a portion of your future equity.

Then you can do a 1031 exchange or sell it at a lower tax rate. 

That’s something you’d want to figure out through tax planning.Regarding the 1031 exchange, bonus depreciation doesn’t affect whether you qualify for one.

The agreement reached was the landlord would lower $100 of the rent (current rent: $3100) in exchange for us to paint the two bedrooms.