I really don't mean to be insulting, but this is sounding like one of those macho bollox trips like a thread (that I forget the title of) last year. You guys are are talking 10hr+ riding days with no lunch breaks, no fuel stops, no rest or recuperation and no allowances for the unexpected. It's bollox... sorry. Possible but fatigue is a dangerous thing.
btw Col D'Iseran was closed in the 1st week of June last year and I believe opened second week. Col D'Galibier was open, but an icy arse clenching affair and only just rideable. One car went over the edge the day before (but with the help of alcohol). No chance for anyone considering May.

p.s. last week , sharing four drivers in a very comfortable car, with minimal stops,cruising at 130kph, it took us 12 hrs Calais -Annecy. No way you can do this with any enjoyment on a bike!