Whatever you do,don't throw water on your brakes,discs could warp.Use a low gear, 2nd if need be and don't keep gently applying the brakes all the time, but checking there is no one right behind you,apply them firmly,nearly stopping the vehicle then let it roll on a bit and apply again.This way they should not overheat.Or if there's a lot of traffic behind,pull over when possible and let them cool down a bit.I've been on hairpins nearly everyday since 6th September, 12 days in the Alps, then Corsica and now Sardinia without any overheating.I'm only in a 3.5t PVC so a heavier van may be a bit more of a challenge.