Its actually not that hard. I've backed up dumpers to the beet clamp ( or pile - my Euro english is getting the better of me ).

When you have the dumper raised, it allows you to see the tyres, which makes backing up A LOT easier. Keeping distance is just a matter of trust, experience, and knowing when your hitting the bumper of the Claas. I don't have an issue with backing up a dumper 300-500 metres and keeping it fairly straight ( 12ft wide window ). I know with sugar beets, the crop is too important to drive over unharvested beets - or at least my ego thinks so - LOL

In a sense, I'm surprised that they do this in Holland. Dutch fields aren't overly long, and so I would think that they would be able to make a round - or at least get to a 'landing' or back of a field, so they can exchange wagons, instead of this. But hey, if the glove fits!!!