Everyone has to make up one’s mind honestly…
Each decides on him in all honesty … Personally we totally understand luggage transport for elderly, or tired persons, maybe even for certain stages … But we see so much excess … because from the moment you make carry, why not taking the hairdryer, the whole pharmacy, th evening dress, the dressing gown (we saw it!) … 
Do not forget that, apart of the cost of the carriage, you will not be free anymore to choose your accommodation and to walk according to your desires; you will necessarily have to arrive at the reserved accommodation, unless a taxi ride …
Luggage of 2 “pilgrims” for 1 week …!
Try rather to lighten up your bagback at the maximum, you will be surprised how little we finally need on the way!
The record that we saw: Dot and John, 2 American pilgrims of 77 and 78 years, left for 90 days and which had backpacks (without other suitcase) of 2,4 and 6,4 kg with the water and the sandwiches!!!
To transport your bags since St Jean you can contact Express Bourricot
In Spain, all along the way, you can contact Jacotrans or the spanish mail.