I use headlight sprung wiper blades as used on such as Volvos and SAABs, these come in a range of lengths from 5" to at least 9". OK need to swap the pivot as described before, but then can use std 'off the shelf' short sprung wiper blades, no need to cut down.
eg
http://www.wiperblades4u.co.uk/headlight-wiper-blades many suppliers on eBay etc. Just a thought - PJB