It is some years now since I was a F/E on Connies and that was on the 749 not the mighty 1649, which was somewhat different to it's smaller brothers.
So on the 749 and 1049 [just looked up the flying manual] on the pilots panel there were just four engine instruements each with a dual pointer
Two of the guages were for Manifold Pressure
Two were for RPM
So the engines could be operated with these basic instruements
However back on the F/E Panel, and only there, were all the rest of the engine instruements and controls many of which could be operated in Auto position, and there were warning lights on many systems to bring your attention to a system/engine problem.
However only at the F/E position were the prop feathering buttons and the engine mixture control, which makes a safe operation by one pilot hard to do.
To sum up the Connie probably could be operated by one pilot as long as nothing goes wrong, and on the connie it often DID