Not going to be much help on hanging your hammock. As much as I would like a Brazilian just haven't gotten there yet. One thing I would like to mention after checking the pictures. Assuming the mallions are open just for moving things around but make sure they are closed before loading the hammock. Made that mistake myself and they will deform to the point of not being able close. Do like your idea of using the external 2"x4", don't recall ever seeing that before.
By the way, welcome aboard
Most of us end up poorer here but richer for being here. Olddog, Fulltime hammocker, 365 nights a year.