I have some initial doubts about the DC load breaking capability of the three contacts in series when the motor is in between. In particular, the voltages between the adjacent contact sets will not be quite the same (much higher) as with the three contacts on the same side of the inductive kick of the motor.
But I could be persuaded either way by someone analyzing the actual voltages.
If the insulation, including arc isolation, between the contact sets is good enough, it should work. The same setup with the contacts on different relays actuated at the same time would give me more of a problem because the contact break would not necessarily be simultaneous. But you have avoided that.