You know your cat best.
We've always taken our cats on longer holidays (although not to the South of France). They've been stressed when left with sitters coming in twice a day, and have got out twice. We also had one sitter (from a very reputable company) neglect to empty the litter tray for a whole week. That was not pleasant to return to, and I suspect not pleasant for the cats either.
We also know our cats, and although they don't particularly enjoy the journey, they much prefer to spend the time with us. We don't let our current cats out, as they're not as reliable, but previous cats have gone for a wander and always returned.
Advice if you decide to do it - A large carrier, so they have room to shift about. We always put a pillow on the bottom for comfort.
A medium sized, shallowish plastic box with a clip on lid. Put a cat litter liner in the bottom and half fill with litter. We put it in the foot well in the back seats, on top of a spread of newspaper, so when we stop for a break we can open it up for them to use. If you've got a big dog crate, you may be able to put it inside, although I wouldn't open it unless you're at a stop.
Same with food and water. Have a small airtight put with water you can put down when stopped. Don't forget that cats won't use the litter tray if it's anywhere near their food and water, so you need to put that somewhere separate.
We do let ours out of their box when we're having a stop, but we're always VERY careful to make sure that they can't get out while opening their crate. This is the only nervous bit of the process, but as some of our trips involve a 4 hour boat crossing, they have to be let out. (By the way, if you do a boat crossing, put towels on all the seats, just in case it's a bit rough).
As I say, you know your cat the best. If you think they'd prefer a few hours discomfort to being stuck home alone with the occasional stranger, or worse, being stuck in a tiny cage in a cattery for 2 weeks, then go for it.
After all, you're not going to be able to from next year.