We are using the Aldi glass cleaner at home at the mo and it's really, really good. I tried it in the MH yesterday too and it works on the non glass windows there too. I cant recall how much it was but being Aldi, its not expensive.
What I like about it is that it doesn't take loads of wiping and drying to get the finish. I have found some need a fair amount of elbow grease to get the surface dry. It also helps that I use kitchen roll to put on and buff off.
Worth a try.