well i thought i might as well post my findings after the weekend. 3 litres of water, two squeezy glucose things and two bananas was all i needed for the 5 hours. the water was a mix of a sachet sport drink and just straight water. so i had a squeezy, a banana and two clif bars in reserve when i finished. pretty pleased with that, didn't fade at all. so i think my requirements are not as bad as i had projected.