How do I structure seller financing?

[Charlie John]

I am going to start a new marketing campaign to reach my goal of buying 2 properties for buy and hold.

Here is my criteria: Town house, built pre-1996, last market sale date 1996.

I am hoping to find original owners that have not made any upgrades or improvements to their town home since buying it 20 or more years ago. Clearly, if there is some distress then that helps! ( smoking in the house, cats, messy/hoarder, etc.)

I am looking to buy these as-is, direct from seller.

My plan is to have two offers:

1. Cash, if thats what they need (70% formula- which would then turn into wholetail/fix-n-flip).

2. Seller financing. I would offer to pay close to market price for the townhouse if they are willing to finance it at favorable terms. That would be a low interest rate(0-3%) and a long amortization schedule(10-15 years). Hopefully, it would help them provide a stream of reliable income and being able to get rid of the property without going through the traditional sales process with realtor. It would help me because with a low interest rate, most of my payments would knock down principal and provide cash flow. 

Have any of you done seller finance for the long term and with low interest rates?