When I built my full-sized ROR back in 2005, I checked local codes and spoke with a contractor. Like many others, my location had a size limit, 120 sq. ft. and you needed a permit, below that you didn't. The requirements said nothing about whether the roof was attached or not. So I made my mine 11'10" on one size, 9'10" on the other side, just under the 120 sq. ft. limit.
As for the ROR external frame, the contractor pointed out that you could build a "patio cover" that was freestanding, of any size, without a permit -- you only needed a permit if it was attached to a permitted structure (like a house). So to cover all the bases I left 1/4" between the observatory and the ROR frame, my wheels rolled right over the tiny gap.
I was also building a pool at the time, so I had inspectors there all the time. One of them noticed the ROR, walked over with his tape measure, measured the length and width, and walked away without saying a word. That was the closest I came to "trouble."
But, mind you, this was out in rural San Diego county, with no HOAs or even neighbors closer than a few hundred feet...