You can ask Coast Guard Yeppon (VMR411), by
VHF, whether the Dept of Defence will grant permission for entry to Island
Head Creek. Or Port Clinton (but IHC is more fun).
My understanding is that Defence only closes Island
Head Creek when a live fire exercise is planned.
Further, I understand that Talisman Sabre is *usually* not live fire (they do use flares and blanks, but usually not live fire).
But you'd need to talk via VMR411 to get DoD approval. DoD won't want you around if they're playing silly blighters on a beach invasion. 'Specially not if you were to take photos of the well-lubricated BBQ, funded by the taxpayer, after playing silly blighters is over for the day.
Bob Norson of TCP fame did a neat description and anchorage guide to Island Head Creek. See:
https://www.thecoastalpassage.com/IHcreek.html