Personalisation + Validation

I've a 'ContentArea' with a 'LimitContentAreaItems' validator attribute attached, but my issue is that the editors may wish to personalize items in the ContentArea, but the validation attribute doesn't take Personalisation into account when counting the blocks in the contentArea. Is it possible for me to write my own custom validator that could allow, for example, 4 items, but 2 items in each visitor group, so that validator will see that there are only ever 2 items enabled at once? So in the example I want to limit it too 2 items, but allow several personalisations such that the contentArea actually has several more items than just the 2.