If you were to impose a Ceiling and Vis Limit on singles that would allow for a visual EOL Landing after breaking cloud....even the fear of Engine Failure would be greatly diminished not withstanding how infrequently they happen anyway.
I would worry more about the single Generator failing than I would the engine failing.
Likewise, Single Pilot IFR in a Helicopter without a nice operable SAS/Auto Pilot system can get very darn interesting too.
At least in the Huey....sans SAS....we always had two Pilots.
Single Pilot IFR in a Bell 412 with a full Sperry Kit was work....but when the Sperry Kit went on strike.....it was an altogether different story......it got to be very damn hard work with not a lot of margin for error.