Black Tank Valve/Discharge Under Coach Rather Than In A Bay?

My 47 year old rig is like that and I've never had a problem and both were original to the rig when I bought it. In most cases, it is far enough forward from the back bumper that it won't be hit easily, and they are at the same or slightly higher point as the bottom of the tank so if you hit them, you've hit your black tank too.