Disclaimer: I'm sure there was something about this kind of topic a while ago, but I can't remember now (and the search is fairly useless).
Would you use this? (NeverWet)
If it works well on plastics and metal alike I'd be fairly tempted to whack a coat on my fairings and just watch the mud drip off... Would certainly make cleaning it a doddle!
They've just sorted a licensing agreement in North America so I doubt it'll be long before it starts appearing in the UK as well...