I'm trying to install the AOA ports in completed 360 wing (wingtip already bonded)

There is a hole in the tip rib behind the strobe lights.

How can I decore the inside of the lower wingskin and install the lower port?

Christian,

 

Is the hole you refer to about an inch in diameter?  If so, it is for the tube that carries wires from the wing tip to the cockpit.  Generally, an approximately 3 inch hole is cut slightly forward of it to access the interior wing skin.  It is thru the larger hole that the pressure pickups are installed.