Sorry, only just found this thread now.
The best place to find the most designs in the one list is:
http://stellafane.org/misc/links.html
I think the 3-pole setup of Albert Highe is a good one for this size scope. I would use at least 40mm or even 50mm diameter tubing. If you look at the designs you can see that the top of the altitude bearing is clamped to the pole, reducing the unsupported length. It is a well tested design used formerly by Plettstone and currently by Dobstuff. My 10 inch version is very rigid.
The Tridob is a good approach but quite complicated to build.
The Obsession UC (a la Greg Babcock et.al.)design is also a good one but requires quite a few steel parts to be cut, bent, drilled, tapped and welded.
I understand that others who have tried the 2 and even 1 pole approach for this size scope have had problems with the poles springing about.
http://stardazed.com/index.html
Looks cool though...!
I really recommend using good quality HCHV plywood For the telescope construction.