Large Running Disc Cage Bracket

I read that running wheels aren't good for rats, causing them to need to arch their backs (tail included) backwards, and run in an un-natural in-ratly (I made that term up) position, and there is apparently no COTS solution for a cage mounted running disc.
The mass of the base for the running disc, I have, didn't seem stable enough for the mass of an adult rat to be able to continuously run without sliding all over the place and then to be obstructed by the cage walls or some other obstruction.
I also didn't like the floor space the non-cage-mounted solution took up; So this can be more strategically mounted just off the edge of a shelf, leaving plenty of playroom everywhere else.

Everything I do will also always be a "work in progress". I didn't put any holes for mounting. I drilled holes and epoxied M4 screw heads to act as studs, with larger 3D printed makeshift nuts to capture two horizontal cage bars per stud.

I printed at 10% infill (to save filament), with 3 vertical sh