Global trigger for vanilla nether portal creation ('Block is placed ' won't work)

Hello,
I would like to trigger an event (which will print "hi" to the console) whenever a nether portal frame is activated, i.e. when a portal block is made. The "A block is placed" global trigger is not triggered by the creation of nether portal blocks.

My current work-around is detecting when fire is placed on obsidian, but this is not ideal and won't work for dispenser-induced fires. 
Any ideas?