Why not if you feel like it
The Tour and Vezelay routes are secondary route to Santiago in France, with very few pilgrims. There are accommodations, but I give you that the one that do exist are sometimes very hard to find. It's not a matter of "fend for yourself and don't bother", rather that France is quite behind in digital presence, information and updates on the Camino... Maybe one of the reason for that is most Camino association members are seniors and so maybe not tech-friendly. (Which is not true for
all seniors, of course!
)
Here's a page for info about the Tour route and
here another about the Vezelay route. On both pages, you can ask for detailed info (with accommodations): hit "demandez notre documentation détaillée", fill up the form and check the boxes for the routes you're interested in (don't check too many or they won't send you anything). It's in French, but manageable to understand and very precious to have around.
I think the trick will be to leave the Tour route and catch the Vezelay route at the right spot. It's so easy to miss the right turn!
Here's a map of your options and
here's a page to explore them. The closer GR after Tours are the GR46 and the GR48. For these 2 and all the other GR you can see on the map of the first link, there are no guides.
If you know how to read maps, I'd advise you to get a topographical map of the region Easy to find, or
here's a great website to DIY: catch-screen, paste in document, print. (Be sure you're on a topo map: "carte" icon in the top-left corner, "voir tous les fonds de carte" button, select "carte topographique IGN").
If you can't read a map, it may be difficult to go from one route to the other, as your only directions would be signposts along the way...
Buen preps