hokiefyd , how often do you get out of the saddle while riding? I feel like some riders just stay planted in their saddle whenever they're moving, and the "sit and spin is more efficient" research has fed into that tendency. I find that shifting up a gear and doing a few pedal strokes out of the saddle every few minutes is not only a good way to help restore circulation, but the jostling of your "stuff" can help you notice sooner when things are starting to go numb.
None of this is a substitute for a proper fit with the right saddle, but I feel it's a good practice.