So if your using margin at let's say 12% interest rate, to do the mentioned S&P gaining at 8% or heck let's say 10%.... congratulations you just found a neat way to go a couple hundred thousand into debt.

We have modified many seller financed notes over the years (with input from the servicer and a qualified attorney as mentioned by others). 

However, as Zane mentioned in his response, another option is to consult with a lawyer who specializes in appealing property taxes.

So as I mentioned, my guess is they co-GP or do something. 

Like others have mentioned, there’s appreciation, depreciation, leverage, and tax benefits that produce a compelling risk adjusted return. 

As mentioned above I would try to work out a partnership.  

You mentioned about the difference between the purchase interest rate and the refinance rate.

It’s more the actual “how-to” or structuring it into the process I’m in, as I mentioned. 

The quiet enjoyment mention is very relevant as everyone is entitled to that.

You didn't mention having other money available.