The foam mast plugs are about 3" thick. If you go 4" up from the side you can see, you should be OK.
Hobie put the foam mast sealer plugs (if they remembered to put them in at all) at various distances into the top and bottom of the mast
Why the cheap shot?
Hobie Cat has made several hundred thousand masts - what evidence do you have that they ever "forgot" to put the plugs in? They've been in every mast I've ever opened up - which has been quite a few in the past 30+ years.
