Yeah - moderate temperature, huge surface area and plenty of air movement across the surface would bring best results. I’m absolutely doing this again next spring, aiming for 20 liters of sap so I can put my fancy fermentation setup to work. Was thinking of using two of those under-the-bed storage boxes to make an evaporating setup, having the lids on and feeding in air with an aquarium pump that has two outputs. I’d still add dark syrup for colour though.