Single pilot IFR in instrument conditions is among the highest workload and most demanding flying you can do. I've flown formation beneath powerlines and run airplanes into burning canyons...and still maintain that single pilot IMC is about as a high a workload, and in my opinion about as hazardous a flying as you an do. Do it single pilot without autopilot, and your workload goes up even more.
Do it in a single engine piston airplane...you're an idiot.
That's my position as a GA pilot and instructor.