Santiago to Bayonne - Looking for transportation recommendation

There are also narrow gauge trains along the Spanish northern coast, from Ferrol to Hendaye in France. My recommendation is to use them and make a few stops along the way. If you have five days, it would be a pity to not visit a very nice part of Spain.

You may also want to fly to Bilbao airport, the biggest in northern Spain, and then take either the narrow gauge train or bus to Donostia/San Sebastian, and then to Baiona/Bayonne by bus. Or Bilbao-Baiona/Bayonne by bus. The narrow gauge train from Santiago de Compostela to Donostia/San Sebastian may be too tiring, as it stops in every little town and in some places you may have to transfer to a bus ride.

After your camino, you might consider flying from Santiago to Biarritz, which is the closest airport to Bayonne. At biarritz, you just need to take a taxi, or a private service to Bayonne.
Flying to San Sebastián doesn't get you to Bayonne, where the tour starts.
Also, 11 hours on bus doesn't sound like fun at all.

Good Morning - thank you for your responses.....

I definitely forgot to mention, I am "old" and travleing solo, so I know not to make plans that are too complicated. One of my concerns as I have traveled in Spain and Portugal on other RS tours, I am unsure about the reliability and regularity of the bus and train schedules, especially when hand-offs are involved.
I do live in Chicago metro and take public transportation frequently.

The responses have given me other venues to consider. Thank you!

Spain has a fabulous public transport system: (very) cheap, frequent, clean, modern, extremely efficient and extremely punctual, as a general rule. So there should not be any worries on that side.