I wonder if any of you outdoor types suffer from eczema, like my (adult) son? His birthday approaches; he walks and climbs, often in hot weather, and has asked for a rucksack that doesn't make his back too hot and sweaty and exacerbate the condition (he will be heading to Greece in August this summer). I'm thinking one with a frame would allow for more air circulation, but we'd be grateful for any tried and tested solutions.