Does installment sale treatment cancel Sec. 121 benefits?

[Ari Newman]

I'm working on a deal structure and am curious to know if it's possible to get the benefits from an installment sale while still capturing the tax free gains from Sec. 121 ?  The structure:

I want to sell my primary residence to an owner-occupant.  My basis in the property is $200K and the sale price is $300K.  I want to take the tax-free gain from the sale, but my buyer can only put $100K down.  Is there a way to carry a 15-year note for the balance of $200K while still capturing the tax-free gain?  (part of Sec. 121 says that the property must have been your primary residence for 2 out of the last 5 years, so that's where I'm not sure if there's a work-around)

Ari