Fannie/Freddie (Conventional) loans aren't just about rate and transfer taxes. 

You should talk to a lawyer.

There's a few other exceptions such as a tax lawyer, but I find that a lot of folks find comfort in just having me respond to any notices that they might get.

@Daniel MadhavapallilYou should hire a tax professional. 

The tax paid from your lending proceeds should be the equivalent of your tax rate I would think.

Hence the lot on which the house resided was taxed at a 45% discount based on actual value, while the tennis lot was taxed at about 4 times what it should have been by value. 

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.  

There are many tax accountants on Bigger Pockets that can help you with your situation. 

If your friends have a rental they should hire a tax professional. 

I am seeking an experienced tax advisor (preferably licensed in CA) with strong expertise in US and German tax law, particularly in real estate investments, mixed income (W-2 & self-employment), and international taxation matters.