Have you tried the RainX Anti-Fog?
Last time I tried it, wasn't too bad
Apart from it being terrible?
Just go for the best and dont f**k around.
http://www.i4detailing.co.uk/cgi-bi...ro_Fog_Fight_9.html#a1_21CPFF100#a1_21CPFF100
Type in carpro fogfight on youtube and the video's alone will sell it.
Its also great to use on the bathroom mirror, write the words 'Boo..!' so the next time some one has a bath and it steams up, they'll be a message on the mirror for em.