Windowlene works well IME, you just have to make sure you don't leave any smears as it makes nightime riding, erm, interesting!! Again, it has to be reapplied regularly.
A cheap tip to help avoid the misting, smear a very, very thin film of washing up liquid on the inside of the visor, being very careful not to over apply or leave streaks in it. This works pretty well but still needs reapplying every time you clean yer visor.
HTH.
