I have three 30gallon tanks set up with ASF's in the same room as all my snakes and geckos. In fact one of the rat tanks is next to a boa tank. I had to put a paper barrier between them to keep my boa from trying to get out. He was always climbing the glass.
The rats on the other hand might not like seeing the boa all over the side of their cage but i find it keeps them in line.