Can we identify the friend from En Hollande, lettres à un ami (1859)?

In early 1857, Maxime Du Camp made a trip to Holland and related his adventures in epistolary form in En Hollande, lettres à un ami (1857). One wonders about the real identity of the anonymous friend who is the intended recipient of his letters. Is it possible to identify him? What literary or stylistic function(s) does he play in the text? Three perspectives are summoned: biographical, literary and that of the reception by a reader who could be seen as Du Camp’s friend.