As others have inferred or suggested directly, DO carry on board all electronics, documents, medications, and other items you cannot possibly afford to lose. Read below for how I do this.
CHECKED LUGGAGE:
I pack my hiking poles and all "sharps" (knife, spork etc) into my rucksack. I place the rucksack in a very bright-colored nylon laundry bag with a pull string closure that can be double-tied. My most recent "find" was a bright lime green, tiny mesh bag, from my local "Dollar Store" for ONE DOLLAR USD.
You will NOT mistake this bag for any other bag on the baggage claim belt. It does NOT resemble any other bag on the planet! I assess that the mesh is too fine to snag baggage handling equipment. I plan to test this in April when I start my next Camino from Madrid. Last year, i used a slightly heavier, non-mesh. nylon laundry bag in a similar color. It worked GREAT. The "used" sack goes into your rucksack as a bottom pad or a liner. It can be used for any number of purposes.
Include a DESTINATION address tag INSIDE the bag, attached to the rucksack proper. Also, on tying the bag securely shut, include ANOTHER, identical, destination tag on the outside for airline personnel to read. Don't worry about "granny knotting" the stings are usually polyester or nylon and will come loose with only a little prodding.
To aid in identification, I recommend you try to find a baggage tag, or tag holder, that contrasts brightly with your shipping sack. So, if you were me (and I am
), using the bright,lime-green mesh laundry bag as a checked bag, you would use a luggage tag holder that was bright orange or neon yellow. I have both.
YOU use a DESTINATION tag instead of a home luggage tag so airline personnel route the bag to, and deliver it to where you will be (Camino starting point), NOT where you were (home).
If starting at St. Jean Pied de Port, this usually means your first night's lodging. I always recommend that people plan to stay two nights at St. Jean PdP before walking, to get over the jet lag, and to experience this wonderful small French town.
They have been sending pilgrims on their way from this town for more than one thousand years. Think about it. Everything you might need as a last minute item is there.
FYI, If so inclined, one of the "best" souvenirs are the locally produced, Basque espadrilles. They are CHEAP and available in every color under the rainbow. I usually arrive with a shopping list from all the women I know.
To aid in getting souvenirs and other items you will not need until reaching Santiago, there are baggage forwarding services (Express Bourricot) and a French Post Office (la Poste) all in walking distance.
St. Jean Pied de Port is not just a starting point. It is a key, historic part of the Camino, writ large. It is the juncture where the various northern routes coming out of northern Europe converge before heading over the Pyrenees and down the "main" route to Santiago. It is profound and humbling.
You SHOULD MAKE A RESERVATION so you have a bed waiting for you. Try
www.booking.com to locate reservable accommodation, including hostals and private albergues.
Address the checked bag according to where your initial stay at St. Jean PdP is. If the airline misplaces your bag they WILL deliver it to THAT address. With any luck it will arrive while you are still there.
You just need to stay relaxed and flexible. Remember, a bad day on Camino is still waaay better than a good day in the office.
IF YOUR CHECKED BAG GOES "WALKABOUT:"
MAKE sure you included your e-mail and text number on the destination luggage tags so the airline can contact you. If you arrive and your "ruck-in-a-sack" bag does not, MAKE SURE you file a lost baggage claim with the airline before you leave the baggage claim area.
DO inform the airline baggage representative you are beginning a "Camino de Sanitago / Chemin du St. Jacques" from St. Jean Pied de Port, so they need to find your bag and deliver it today or tomorrow at the latest to THIS ADDRESS (on the attached tags).
Better yet, if you have a photo of your "ruck-in-a-sack" on your smart phone, taken just before you checked it, so much the better, as you can show them or send it to them. A close-up photo of the actual external destination tag is also a sage idea. This is the classic "one picture is worth a 1000 words" scenario.
MY CARRY-ON SOLUTION:
When I am on my way to start a Camino, my carry-on bag is typically a sil-nylon 20 liter daypack. On arrival, it gets stored for use along the Camino. It is my shopping bag, laundry bag, and "possibles bag" for touring cities and playing tourist.
In North America, Sea to Summit offer a complete line of both day packs with shoulder straps and slightly smaller (16 L) shoulder bags. I have both, bring both, and use both. Check here for suggestions:
http://www.amazon.com/s/?tag=casaivar02-20
You should consider, IMHO, both the 20L daypack and the 16L Sling Bag. The latter is a zipper-top shoulder bag, more easily worn together with a rucksack on your back.
I hope this helps.