I have seen few examples of designs for line arrays.

The test baffles I've made are all open.

There was a project shown here a while back where a
triangular enclosure was used behind the speaks.

What occurred to me was: could such an enclosure be
made out of a split piece of 6" PVC sliced down the
middle with a cap at both ends?

I was looking at Dr. Griffin's white paper and
the diagram of the front wave made me think of a curved
reflector in back.

However, I have no idea on how to model such a thing
with 8 drivers that cost 50 cents each. The sealed boxes
I've had experience with tend to muffle the clarity of
an open baffle system just about every time.