Sonnet ink evaporation fix

I hate Parker Sonnet pens — and we still have two, after I gave a third one away decades ago — and, to a large extent, it's because their caps are invariably useless at preventing ink evaporation, because they're not airtight. From reading the Sonnet ink evaporation fix thread, it seems that the inner cap shouldn't vent into cavity between that and the exterior metal cap but does anyway, and the gap in the cap finial then just makes continuous evaporation inevitable.