In spite of it being possible (I think), I do not recommend the 18 CP1700 cells. I have once again looked it over and I have trouble finding a place for the ESC without having some l-o-n-g wires. Of course I do not have the motor you are going to use but I don't think the overall length is greatly different than my geared Pletti. That could be a very poor assumption. Also, the weight is going to be well over 2.2 kilos. You will have a speed demon for sure.
I would suggest swapping the motor for a different wind or just using 15 cells with what you have. However, if you press on I certainly want to hear about the results!
Gordon, I think you are right after all!