Have you checked out a Tentipi? Tentipi is a Swedish manufacturer that's been making tipi style tents for many years. I recently saw that they have a new North American distributor based in Seattle - www.mansfieldoutdoors.com

Their Zirkon 15 would seem to be a best of both worlds for you. It's a huge single center pole tipi, but made of cotton canvas. Seems like an ideal cross between wall tent and tipi, although I confess I've never seen one in person.

Good luck!