Pete- you are surely the guru upon such matters. Plan is to C2C Iceland next August for my surprise 40th birthday present. North to South. Kjola route is the plan at the moment but seems a bit too busy for my liking. Preference is to be totaly self-contained and self reliant. There will probably only be 2 or 3 of us. Everything has to be carried inc. a bottle of wine, and water at some points. But there are thermal springs to wash away the days aches and pains though...
Back is OK and is used to a fairly full daypack of 8 kg or so. Not sure of milage, 40 km would be nice, perhaps more. Daylight is not a problem, it doesn't really stop up there in the summer. It's my birthday, I'm a teacher. Budget is fairly 'flexible'. Just don't tell Janice. As for the surface- well, the Apollo missions trained there. And nowadays regular bus services run over the route.
having said that, the last time that I was there (a long time ago)I helped to push a bus out of a glacial river, and was presented with a whisky on the rocks as my reward. the rocks were small bits of glacial ice just floating past in the waist deep water.
I rode that route a couple of years ago with standard gear - Blackburn rack, Ortlieb panniers, and several packs of camp food. Running south > north, took 2 days! That was because of the crazy tailwind ... hardly had to push at all.
Couldn't say it was busy in the slightest. Just a few cyclists and the odd 4x4.
Good trip. Liked Westfyords most - lots of ups and downs....