I have also been following a 'Forced Exercise' routine that has proven to work for parkinsons too. The idea behind it is you are exercising at a faster pace than you'd be able to do yourself so in humans they had a patient on the back of a tandem so the person in front was setting the pace or they used static exercise motorised pedals (I did this one) which enabled the person to pedal to faster than they would be able to do on their own. It reduces involuntary movements such as intention tremor because it stimulates a different part of the brain than what you use to exercise/move at your own base. In theory this should work for a dog too.
Now obviously a dog can't ride a tandem or exercise pedals!
.. but this theory could also work with a treadmill if you have the dog in an harness to support its body and are on the treadmill with them (or alongside for a larger dog) and slowly build up to a quicker speed. the dog's feet will automatically move especially if they are slightly highered, obviously this would be easier to do with a small dog than a bigger one.
Swimming (with a doggy life jacket with handles) could also work with someone pulling them along at a slightly quicker pace as the dog is working it's legs. combined with letting them swim/walk at their own pace too, it could be effective in reducing the intention tremor the dog with Cerebellar Ataxia gets when it tries to do intentional movement (walking, getting food from a bowl etc) as I've noticed a few cases online where it's mentioned the tremor is not present when the dog is resting/sleeping.