A map or even Polar-readout won't help you with gearing. An average rider will simply want an average gear.
Bring your 2:1 and something longer or shorter. But it won't matter much for your speed, as there's plenty of climbing to make a long gear hurt, and enough flats to spin your brains off. The perfect gear won't help, your lungs and legs will decide. Last year's podium studs at the Open Dutch SSC on the same course all had very different gears. One man was even pushing on flat pavement, and another seemed to even be spinning on the hardest climbs. Differences between finish times were minimal.
Most important performance-enhancing feature to bring along will be eyeflaps (like a horse wears) to not be distracted by the ladies present along the course who'll be contesting the Dutch Students Champs on the same day.