To be honest, I don't have the practical experience on a CD-22 to answer that other than SWAG*. 9 ft. overall would certainly hang over one end or both ends of the cabin roof/brow, but only by about six inches. Mounting for travel, however, is an entirely different matter.
Once concern with a radar arch, for me anyway, is that my old inflatable had 15" tubes, and considering the added protuberances on the tubes, it would need some careful arch measurements and location to keep the overall boat/trailer height down to my personal comfort levels while leaving enough room to slip the dingy below the arch. Right now I measure roughly 10 ft. from the top of the radome to the road, so my gut level clearance is set at 10'6" minimum. If I had an arch with, say, 18" clearance between the arch and the C-Dory top, my overall height would grow to 12 ft. That surpasses my "Of no concern" comfort level and moves into the "Do I have clearance at that gas station?" level. I've even seen railroad bridges with 12' clearance while RV'ing and a new radome ain't cheap.
*SWAG
Scientific wild ass guess