Cantilever is fine... just use 2 mounting rings. The wife had somebody mount her Ultradot with one mount... eventually broke the front lense. I mounted it with 2 and have not had any issues.
Even with perfect glass (I mean that literally) the bullet impact will only be precise when in the center of the optic: a 1” optic will vary by 1” from edge to edge. This effect isn’t parallax, it’s the nature of the technology.
To shoot perfectly you need to keep the dot centered.