Greetings Chette
We will have to disagree on the "gospel of Philip"...I do understand that Acts is a transistion book but there is no gospel of Philip in my opinion.
But, even so, I still think the verses I quoted apply.
Acts 8:38 And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him.
39 And when they were come up out of the water, the Spirit of the Lord caught away Philip, that the eunuch saw him no more: and he went on his way rejoicing.
I find it hard to believe that Paul changed "how" to baptize and see nothing that suggests he did.