In reply to timw1:
Did the Goƻter route end July, crossing the couloir was not a big deal late morning on the way up and early afternoon on the way down. There were sporadic discharges of mostly small rocks, maybe every 10-15 minutes, but you are exposed for all of 20 seconds. If there's nothing on its way down when you set out, there's not much danger of being hit. Plus the climbers higher up on the ridge set up a big racket when anything comes loose.
The biggest problem of the return was having to wait 2 hours for a place on the Tramway du Mont Blanc, and then another 2 hours to get back through the Mont Blanc Tunnel (my car was on the Italian side). Things to bear in mind for the logistics of the trip.
As for bivying at the Gonella hut, I don't know anyone who's ever tried it, but the place is on a rocky spur above the glacier and there's not a lot of flat ground. Also, if you're planning a traverse, the Italian normal route is very long (+1,800m). If it were me, I wouldn't want to be packing any extra weight. You shouldn't have a problem getting a booking at Gonella, but maybe a day's notice is a bit short. Usual practice is to book early and confirm 2-3 days in advance when you have an idea of the weather.
Using lifts and huts is not cheating. They're part of the Alpine experience. Unless you're strapped for cash of course, as they are not cheap.