So the question becomes based on their individual and personal tax situation what is the estimated tax burden they'd save? 

The key is that in order to completely defer all tax you must purchase at least as much as your net sale. 

Looking for various tax strategies to reduce the reality that a large RV or boat is a grossly depreciating assetI would not have a loan, so claiming it as a primary or secondary residence and claiming the mortgage deduction is not applicable.I sold my primary residence and I have several rental properties which I use as I'm fixing them up.What I'm pondering is living aboard and working aboard developing a new product, while traveling.  

How is it a tax strategy though?

You may be able to deduct mortgage interest and property taxes before the property is in service. 

How is it a tax strategy though?

Whether you need a CPA with just three rentals depends on the complexity of your situation and your comfort level with DIY tax prep.If things are pretty straightforward, you might be fine with tax software for now.

Anyone answering is not responding as a Tax accountant, Insurance expert or as a Financial advisor.  

Somebody bought that house at Tax Sale.   

@Caryn FischerI agree with Jaron, you should definitely have a consultation with your tax accountant and/or financial planner before you do anything.