No doc (no employment, income or assets) requires 20% down/equity... down the road they could be completely eliminated, I wouldn't make plans on qualifying for a product like that. The way a refinance would work is essentially the "option price" is used as the payoff amount, you aren't refinancing, lenders just treat it as a refinance when it comes to qualifying... meaning the current appraised value can be used instead of the option price. You need to have a recorded land contract & at least a 12 month payment history in order for it to work, and you risk the chance of that guideline being different when you go to execute your option.
Make sure you have the option to purchase it at the current appraised value rather than the agreed upon option price, if the home doesn't appraise out at the option price it doesn't matter what type of arrangement you've had... the appraised value will be used by the lender.
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