I was always kind of scared of flying in IMC in cloud in the winter and for the most part avoided it. I did get in some once in a Cessna and it was worrying with some large pieces of frost like substance coming through the air vents.
Doing this at night is not a wise idea. It looks like avoiding weather painted on ATC radar is a good idea as well no matter what the forecast was. Another key is the ground temp in terms of being able to melt any unanticipated ice accumulation. If it is cold, another reason not to go. I would stick to mostly clear nights and only thin clouds in the day when on an IFR flight plan in the winter in these unprotected light aircraft. And have extra fuel and be ready to deviate/divert.
Looks like the situation was subsequently handled well with carb heat on(the intake filter is completely iced over) and a no flap landing.
Twice I had to descend to find the warmer air, and was very lucky it was there to be found, the other time, was as a 15 year old passenger in an iced over 150, where sheer luck allowed us to break out on top, and stay aloft long enough, that sublimation removed enough ice to allow a decent approach hours later.
A friend of mine (highly experienced retired test pilot) was ferrying a Piper Dakota (lots of power available). He encountered unforecast ice over Labrador, at night (which was probably not the wisest time to be flying there). He told me that full power allowed him to maintain 75 knots on the buffet of the stall, while he descended at 1500 FPM. He hit the trees doing that, and spent a cold night, injured and trapped in the wreck, waiting for rescue the next morning. Six months later, he flew again.
Be very scared of icing in non known ice equipped planes. Be cautious of ice in known ice planes.