Unfortunately I don't think finishing in Courchevel, at least where your stage finishes, is really an option anyway. The crowds coming to the mtf of a TdF stage are way too huge to descent through on the way down to the valley. I'm highly critical at any attempt of using the same piece of a climb in two directions but I think at the Tour that's just a complete no go.Thanks, that was me.
The problem would probably occur when the front group starting climbing to Courchevel, becuase it's only a 28 Kilometer loop, most of them downhill, 5 kilometer slightly uphill and 10 kilometer at 6 percent, so the grupetto can't be much more than 40 minutes behind. So the most likely stage like that would probably be flat until Col de la Loze, to avoid to big of a time gap.
Full stage: https://ridewithgps.com/routes/41304657
That said, you could use your route but instead of going all the way up to the airport just finish in Courchevel Le Praz like the Dauphine in 2014. No road would have to be used twice and I think that climb is much better suited to be placed after the monster that is the Col de la Loze anyway.