When I was looking for the hardware for my chain link pens, I checked out dog kennel manufacturers. Several had parts catalogs. The T clamps come in many sizes. There are also other configurations like ones for going from one size pipe to another size.Those T's are hard to find around here. Might have to get se from Amazon. Thanks for tbe visual.
Have you considered corrugated tin and corrugated plastic in clear, green or smoke for your roof material. Here Lowe's carries the corrugated plastic. Farm supply companies sell corrugated tin in different grades...definitely would need to get a thicker gauge for heavy snow. Ridge pieces come in ventilated or non ventilated...some more expensive versions have closeable louvers.Heres where were at so far. Still a work in progress.
I can't remember who posted these photos on another thread here on BYC, but I saved them in my ideas folder back in June.
These are made with cattle panels. Would probably need more closely spaced structural supports, but the owner said they have snow.

