If you're subject to the Alternative Minimum Tax (AMT), these deductions may be limited.

If you feel ambitious, you could try a BRRR strategy adding additional equity to the subject home and then taking equity out of it to pay off either the HELOC or if you decided to the refinance the primary residence. 

Even if the property is short, a contract with a buyer, even subject to short sale approval, should work. 

It will have a detail breakdown of comps and their values and a breakdown of the subject property.Title Work - This is all on you. 

I understand the concept and it may be useful for some people who have difficulty managing their money by giving them a structure, but I do better myself.That's cool, but this is what's hard about this subject.

When people bring up Subject To (very risky) and private money it's usually because they have seen a lot of scaling content.

Personally, I'm incredibly ignorant on the subject compared to others, but find it fascinating.

Put together a spreadsheet and compare the performance of the subject property if you keep renting it as is for the next 10 or 20 years versus if you rehab and refinance.

I guess, I think that you are asking the question as if the answer is subjective when it is actually objective and you can look at your numbers and see where you are at.

Only trick to this would be if you do not own your current primary residence and you do not have a current housing payment, then no rental income from either the upcoming subject property or investment property can be utilized towards qualifying.