I personally would sell privately, especially with such a desirable car.
Providing you have the time and are prepared to put up with the tyre kickers and low ball offers then that would be my course of action as you only require one serious enquiry with no p/x.
You would then be free to shop around and negotiate a discount on your next car for not having a p/x.
Hopefully, with getting a premium price for your Nismo and a discount off your next car, I only see this as a win, win.