I grew 3 crown prince last year fidget and they were indeed rampant - they grew to well over 6m! I left them to their own devices but only had one or 2 fruit set per plant despite hand-pollinating - each was about 4kg, so I suggest some control may be better and might produce a greater number of more manageable sized fruit. Perhaps try that with one or two of them? This year I also have a couple of them and am going to pinch out the main growing tip at 3m as an experiment and when side shoots develop, pinch those out after the first fruit set on each (if they do..) In addition I have several other varieties and harrier are my best hope for the future - they are producing female flowers much closer to the centre and are supposed to be bushy and less spreading. We shall see! Also growing barbara butternut, autumn crown (blurb says average 5 fruit per plant and a bit smaller than c.prince) and pumpkin summer ball which I can't praise highly enough - extremely compact, incredibly productive (think courgettes!) and also store much better than I thought they would. They are a regular here. If no-one else with more experience chips-in, perhaps we can report back on this thread about developments/results?
edit: Edd replied while[ I was typing, so looks like pinching out is the thing to do.