First, let me say that it has been documented here on ball-pythons forums... that nobobdy from this site feeding ASF's has ever had any problems in time switching back to normal rats.
That said, I found the two biggest things that lowered odor when I had rats was the equine fresh substrate (this is also the most cost effective) and a small fan blowing towards the tanks 100% of the time.
In my opinion the fan made the biggest difference... It was not on them in a way where the rodents would be blown away... I set it just right so there was a constant flow of air over the top of all the tanks.
Bottom line though is that rats stink. GO ASF!