Monsieur Ben goes slowly up mountains like Nairo Quintana goes slowly up mountains!
Lovely idea, Martin. Is it enough of a challenge though? (LEL = 1300k, MV = 21k approx) And as mentioned above, it's a long way to go for a morning's ride! Would recommend spending the same day/following day on the bike, on great roads among great scenery.
3 things to be aware of:
1) le soleil - likely to be strong at planned time of year. This is not to be underestimated. After Chalet Reynard, there is nowhere to hide. And the 'lunar' like surface reflects the heat back. Hydrate well.
2) le vent - the mistral can be a bugger any time of the year. Again, after Chalet Reynard, there is nowhere to hide. Hope for calm or a tailwind! I was discouraged from the ascent because of a 30kph breeze, gusting to 50kph and, the previous day, when the wind was more gentle, a bloke got blown off the edge and ended up in hospital, apparently.
3) les mouflons - the wild sheep. Actually, these are mythical animals but les moutons do reside on there. And they do not seem to be afraid of cyclists, unlike english sheep who tend to runaway when approached by humans. It is inadvisable to round a bend on the descent to find a small flock across the whole road!
So, it is not too difficult, if you like hills, but it does command respect. Go for it!
'...SWMBO is expressing concerns...' to be shared on CC? Maybe they can be alleviated.