If you go carbon pole, I would use a 4" dia.

The compression strength is increased by the cube
of the increased area. 2.5 to 4 is huge.

I don't believe Wouters analysis of being able
to rid yourself of compression loading is correct.
Unless you can get the mainsheet to pull on the boom
at 90 degrees and you can get the clew to align
at that point (you can't) you are doomed to having boom
compression. No big deal. If your existing deflection
is minor, consider living with it.

Nice boat.