American Toads-- solitary or communal?

[Yelikosium]

I'm aware that American toads are generally solitary in the wild, but what would they prefer in captivity? I currently have two toads in a ten gallon. Tomorrow, I'm buying a 20 long. Would one toad be happier getting a whole 20l to himself, or should I keep the pair? I know they tolerate eachother, but does the presence of another toad add to stress? Conversely, if u were to just keep one by itself, would it be lonely never again seeing a member of its own species? Any experience on the subject would be appreciated.