But it doesn't help me for my current situation.

@Rob Brown Your asset allocation should be determined by your personal financial situation.

I have done rent reductions for things like that in the past but it depends on the situation.

But I’m not sure what my situation would look like if I did acquire more debt. 

I allow co-signers in certain situations.

In the right short-term situation where you can buy them out quickly by refiing the property as you suggest I think it works well but those deals are very hard to find for people with deep experience and connections in that local market so for someone with no experience and no local knowledge it's going to be nearly impossible.

It seems to me that even in the perfect situation, where I get paid like 12% interest rate with no chance of default, and I get a HELOC with around 6% interest rate, I'm going to have to pay taxes on the interest I collect, but I cannot write off the interest I pay, and it will probably not be worth it.

I have listed my rental home of 6yrs for sale, our situation me and wife are working and the capital gains tax quite doesn't look correct.

Unless everyone is completely stupid and didn't learn anything, the situations that caused the 07 bubble are not whats going to cause the next one. 

That way if any tenant in the future has issues or questions about this situation you will be covered from a liability stand point.