I just returned from this way. I would like to share some thoughts.
I walked alone from Bordeaux, south west to Biganos then along the Voie Littorale / Voie de Soulac down to Bayonne. Then I met my younger brother and we walked from Dax to Muxia.
Firstly, Thank You for your help and advice.
My observations on the Voie de Soulac:-
This is a humble way with very few other pilgrims.
This walk is mainly on sandy trails in pine forest, there are some areas of corn plantation amongst the forest. Sometimes the sand is very soft! At times you walk on tarmac bike tracks and along roads. You walk around lakes and near the end of the way approaching Bayonne you can go to the beach. In fact at Labenne I stayed near the beach for four days to let an angry toe heal. (Don't worry it happens to me on all long walks). Those four days were great, renting a bike and acting like a local. Good times.
The way markers are yellow arrows on blue background, a few inches in size and stuck on poles and trees at about six to eight feet off the ground. There is a marker each time you need to take a turn. Thanks to the Amis Les Landes, they have done an excellent job.
The guide "The Voie Littorale: Soulac to Hendaye" found here
http://www.csj.org.uk/guides-online.htm is a must. It made the way easy to find and at one or two places where a marker was missing helped me a lot. It also let's you know some history.
Accommodation:-
Here is the list for pilgrim accommodation from the Amis Les Landes
http://www.xacobeo.fr/ZE1.11.Aqu.Lit_Lan_heb.pdf sadly their website is not working.
The CSJ guide lists accommodation from that list.
The above list transformed my way. Getting that list made all the difference. TAKE NOTE if you walk in France, get the list of accommodation from the Amis St Jacques for the areas you are walking in. It will save you much time and money.
The accommodation listed is simple, it ranges from a two bed gite, caravan parks where you can hire a van for 10 euros (some were old, one was a huge 4 bedder) and others where I used a tent. Of course you can stay at hotels when in villages that have them
MAPS
The best ones I found are here:-
http://www.xacobeo.fr/ZE1.11.Aqu.Lit.htm
This way is solitary. I met two French couples in their fifties at different times and walked with them for half the way, but the rest I was alone. I found this great as it allowed me to practice French with them AND be the pilgrim and pray a lot when I was alone.
The walking is tough going in some ways. It is mediocre in that their is a lot of sand trail walking in forests that go on and on, sometimes that is tough going as the sand is soft.
If you walk with a tent forget about camping amongst the pines, as there is a spiky undergrowth that makes this impossible. Plus trees fall in there. I saw a few trees that had fallen. Water is not available in the forests either.
Old stuff- there isn't much in terms of old churches etc on this way. If you are into history, give this way a miss. The current way is not the way that was walked in medieval times as that follows the highway further east.
In summary, this is a nature way with few other pilgrims. It's well marked and the guide is great. Accommodation varies and the local people are cool. They were generous and welcoming.
One last thing, if you know some French they really appreciate it.
Feel free to message me if you have any questions. I would be more than happy to help out if I can.
michael