Of course when I do sell, I'd love to have it listed at the correct square footage, but would there be any type of back taxes owed since the assessed value has been off the 800sq foot number?

Check your most recent assessment.

I've seen bad assessments and management destroy peoples lives in retirement because they have no control and can't absorb the impact of bad HOA management.So I guess my vote would be to sell and look for higher NOI, passivity, and protection against any kind of market correction. 

Is price per square foot an accurate assessment that a property is a good deal?

I’m not too sure as to where to start with assessing costs yet.

@Jennifer O.I like your assessment of the existing leases.  

You're nearly doubling the value of the property, should you expect the taxes to double at the next assessment?

Mine is 1.4% but there is an exemption for residential property so it's taxed at 45% of assessed value.

We pay city and county here and no way $3100 a year covers both for that valuation/assessment.

As a result, the local county assessor will likely keep assessed values (and thus - property taxes) somewhat aligned with sales prices.