It IS a fact that aircraft are obliged to fly in cloud without a radar service, it happens quite often. I'm not happy with the situation when it occurs and will try to change level to gain some sort of in flight visibility if at all practical. Sometimes it's not (icing conditions or airspace above, or terrain below. TCAS is of some help but not by any means the full answer, as indeed a radar service isn't the full answer in class G.
I always try to tell folks how valuable Mode C is. If fitted, use it please - TCAS means I can avoid you and we are all safer.
As far as staying on the ground if it's cloudy? I wish!