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Are we talking about a 'Morris' minivan shape or an American people carrier...if it is the latter I can understand your concerns about excess roll.
KPI is only there to ease the stress on the wheel bearings, but together with castor angle, it does create scrub if the wheel is turned from lock to lock when stationary. You have to base your calculations somewhere and the centre of the tyre is a fixed point, in effect the car is moving about this point It is of little consequence what the inside, lightly loaded front wheel is doing while cornering.
Ackerman discovered a 100 years ago that if you align the steering arms with the centre of the rear axle then the inside wheel will follow a tighter radius than the outer wheel, hence no tyre scrub. Racecar designers often use varying ammounts in anticipation of the outside wheel doing most of the work and having a greater angle of slip.
Current racing cars run varying degrees of negative camber to keep the tyre contact as big as possible, and that is with minimal suspension travel. With a dual purpose vehicle if you were to be able to design out camber change in roll then you would be left with extreme camber and toe in changes during bump and squat......it's all a compromise!
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