Couple more things to add for future reference:
We stayed at the Ferme Noemie campsite near Bourg-d’Oisans. Highly recommended. It’s a small campsite run by an English couple, but for things like the TdF, they open up a couple of small paddocks to increase capacity. It increases pressure on washing facilities etc, but not stupidly. We did not have a hookup, but solar power kept the fridge etc going fine.
Secondly, we did a tour of the big cols today in the van - Telegraph, Glandon, Croix de Fer, Galibier and Alpe D’Huez. At no point did we feel short of power in our 102 bhp SWB van (about 2.5 tonnes I reckon). It easily kept up with sensible car traffic. The brakes were a bit toasty after Alpe D’huez, but they never faded..
Really impressed.
Pete