Removing Water Pump Housing

I've taken the water pump out to replace and am thinking about removing the housing as well to replace that gasket. But....the bottom bolt seems impossible to get to without removing that large wheel and counterweight (?) in front of engine. Is there a way to get the housing off without doing that?

I am worried that the leak is behind the housing and replacing the pump may not do the trick. I still see water on front bottom of engine after two days of having the pump off.

Nic
'85 300CD @ 149k miles