This means if TSHTF, I still get to keep the house without any outstanding mortgage or HELOC payments to worry about.If I ever need to use HELOC or term loan on my otherwise fully paid off primary residence, it will most likely for short term, such as a rehab unit which will eventually be sold or refinance. 

I understand your concern when you are seeing many people investing in the outstanding opportunity in SWFL. 

Throw every dollar you can at any outstanding debt, then save save save.

To send it to the auction though, you have to pay off all the other outstanding certificates.

Outstanding local RE attorneys 

There is also an outstanding gas bill.

Also, you want to make sure you have paid off any outstanding debts, and the like.  

Selling a $250k property with $50k outstanding or $200k outstanding has no impact.

Is there a rough percentage of the outstanding balance that the banks will accept.  

If I continued to make the same amount at my job and rents stay the same, I would be able to put about $10,000 per month towards the outstanding balance of several mortgages.