Tax implications of building an addition & selling it as a condo?

[Alex Asen]

I own a 2,000 sq ft single-family outside of Boston, which has been my wife's and my primary residence for 2+ years.  I have ZBA approval  to create a two-family by building a 2,000 sq ft addition mostly in my current driveway, but there will be some overlap between the two units.

After construction, I plan to split the units into two condos.  I will continue to live in my current space and sell the second unit.  

Is there any way to structure things so that that sale of the second unit qualifies for the home sale exclusion? 

If not, is there a way to at least qualify for treating the sale of the new unit as a capital gain?

Thank you so much for your help!  I am clearly in need of a good accountant, but have been struggling to find one...