Don't overengineer this.

All you need is something you can attach in a way it doesn't move under
the small pressures needed to deflect dial indicator's plunger.  A
magnetic base is fine and you could probably put it on the strut, at
least in the front; a clamp base is also fine so long as something in
the vicinity is within the range of the clamp's jaws.  Both kinds of
adjustments (rods with clamps and flexible goosenecks) are likewise
fine.  If all else fails you can attach the thing to the floor jack and
still get a good reading for disk runout.

Mine's got a magnetic base and rods and clamps, but only because that's
what was available where I bought it 25 years ago or so.  I've never
failed to find a way to use it when I needed it but YMMV.

JRE

I always used an axle stand and a screwdriver.  Discs are either true
or they're not.   In my experience most problems diagnosed as warped
discs actually turn out to be suspension wear usually in the bushes.