I am trying to contact Mr Tulot home but he is always absent. As he has not an email I will write by snail mail. I don't know if his books are available in the US. I guess not because they are not translated.
About James Boisseau: it is the only name and the only birthdate corresponding to your datas. The birthplace (Saumur) is different because the town Montauban is a very little town near Rennes and the Huguenots were used to go to Saumur to make their baptisms. Moreover, Mr de l'Espinay checked every entries in the records of Montauban and found nothing. We cannot say for sure he was the man who left France for England because after having fighted with the Dragons I don't think they were able to record anything anywhere on their departure. In conclusion I would say he is the man because there is no other possibility.