Seller-financed, 7 year amortization

[Scott Smith]

I took part in a deal in South Florida where the seller financed his home at a steep discount to the appraisal value, in exchange for the right to live there for a few more years. The purchase price will be paid in annual installments over 7 years, 0% interest. The result is an annual cash payment of 90k directly to the seller. I make the annual installment with cash flow from other properties and some w2 income. I owe 405k and the property is worth 1.2M, according to the most recent appraisal. 

Coming up with the annual installment has become a little painful, as I am working a w2 that I would otherwise step away from. The whole rent-back situation is unconventional. I'm looking for ways to reduce my annual outlay of cash, even if i have to give up some equity, and get back to "normal" investing. 

What's the solution? Cash-out refi?