I would spend some more time on building capital so you can make sure you have money for reserves if things go wrong. 

As far as the other property, my ultimate desire is to build a duplex for rent. 

After researching online I found landlord responsibility under California Civil Code section 1941 described as followsClean and sanitary buildings, grounds and appurtenances (for example, a garden or adetached garage) which are free from debris, filth, rubbish, garbage, rodents andvermin. 

- I haven't been able to find any 1031 opportunities (buildings or otherwise) to roll the money intoI appreciate learning your thoughts on whether to sell and keep.

The Columbus macroeconomics is booming due to many companies building out here like Intel, Meta, Google, Amazon, etc., and there is continuous population and job growth!

But then I bought my four unit building in the Twin Cities, and partially due to time of year, and partially due to schedule, I called them in after our fall rehab was done, and they have done a great job getting me tenants....and they warranty them for six months.  

Quote from @Richie Linnon: I don't recommend small increases over a long period of time because it increases the chance of mistakes, it may still build animosity with the tenant, and the tenant may eventually reach a point where he can no longer afford the increases and he will leave.

That being aid, if you're trying to get a HELOC or any other fully documented loan, the lender could ask for your tax returns. 

The more relationships and marketing channels you build will only benefit you in the long run.

What strategies should I employ to build a professional network within the real estate community?