I kinda/sorta had the same question about my 2010 12' 6" SUP'er.
I can SEE through the two rear inserts into something white, looks like EPS foam.
The front one ?... I have been ASSUMING that is the vent plug, but with no manual I am not so sure.
Anyway, I am nervous of hacking up the EVA pad in case I do it at the wrong spot.
Do I really NEED to remove this, or can I just bolt directly down to those inserts ?
BTW, should I buy a 2 bolt base ?
Any chance of some pics of this, just so I get a better idea of what I would be cutting towards ?