I use an ammonia-based window cleaner as the 1st step in my cleaning process because it is cheap, easy to work with, cuts through the crud, it is cheap, transports better than hot water (I do this cleaning step at the range usually), and as I understand it, helps remove some of the copper fouling as well. Besides, it is cheap - I'm still working through a gallon of concentrate my wife bought several years ago...
From what I've been able to tell from reading up on the chemistry involved, hot water really is the best way to remove the corrosive salts. A little soap or other surfactant helps remove some of the other crud, ammonia cuts through grease and oils, so ammonia-based window cleaner seems to me to be the best option when lots of hot water isn't easily available.
Just a Shooter