While waiting for a direct answer, for the commentaries you might like to see 'How was Caesar's "Gallic War" created and distributed?' at https://www.reddit.com/r/AskHistorians/comments/7g0ur5/how_was_caesars_gallic_war_created_and_distributed/ , multi-part reply by /u/XenophonTheAthenian . They get to the third-person issue in the middle of the second part, but you might want to read everything up to it to get background. (And everything after just because it's cool.)

But linking to a previous answer is not intended to discourage more discussion. Further questions, data, and debate are welcome.