Since each taxing municipality has different mill rates (property tax rates) a 1031 exchange into a state or municipality within a state where the mill rate is lower can help. 

One of the terrible pieces of advice I received was from 2 people who suggested that I sell my California SFH rental (with lots of equity) to "cash flow" more and "acquire more doors" by doing a 1031 exchange into an apartment complex OOS or buy multiple SFHs/duplexes OOS.

I think we could exchange some valuable insights!

I would try and do a 1031 exchange.   

Under IRS rules (see IRS Publication 925 on Passive Activity and At-Risk Rules), when you sell a rental property, all suspended passive losses from that property and the rest of your portfolio become deductible in the year of the sale, provided you fully dispose of the activity and it is not exchanged for another property (like in a 1031 exchange).If you have $100K in losses from your entire portfolio, those should be applied to the capital gain from the sale of the property—not just the $50K from the specific property being sold. 

Is there a way to put this into a 1031 if its considered my Primary residence?

If the property is bleeding money every year from repairs, maintenance, or turn over you'll never get ahead.You can tap equity with a HELOC (challenging right now), cash-out refinance into a new loan (much higher rates), 1031 exchange, or sell (tax hit) but the numbers and property condition need to guide this decision.

I’ve periodically had tenants at the Multis offer to “help with the landscaping” in exchange for a discount on their rent.

 Flic and Flips don’t typically qualify for 1031 exchange tax benefits. 

I've heard from several people who thought they had an owner finance agreement signed at the kitchen table, assumed they were paying down equity only to have the house sold right out from under them.Ben,  How common is this that a seller is willing to give up their deed upfront in exchange for seller financing.