Roll inertia estimation from aileron performance, to gauge wing tank levels? Have to assume ailerons are performing 'nominal'.
Other than a nerd-sniping exercise I don't see the point of going down this rabbit hole, because on an aircraft with pax the pilot's job isn't to screw around playing Chuck Yeager and estimate fuel with test pilot techniques.
If they can't fly with confidence that they're safe, then the pilot's job is to put the fucking aircraft on the ground as soon as able.