try and use a duster with a rubber grip, it well protect against accidental drops and the ensuing dents/dimples.
http://www.autopia-carcare.com/oxo-1050580.html
The Das Schield? trunk and hood interior shields are expensive, but well worth it. One tiny dimple can ruin the entire look.
and aside, use Lexol (brown bottle) on the leather seats, warm up the car first. Its important to keep the leather moisturized during winter. If the leather dries, the tell tale cracks of dry leather will visit your Boxster. The Lexol is also good for the steering wheel. Driving gloves also help.