Hi Dave,
Had a similar problem in New Cal in May this year.
Fishing a reef opening - bait, colour change, scum line - the fish had to be there.
Popper after popper, stick bait all and sundry were tried and finally Etienne the Guide flicked out a big Squidge Fish = Big GT.
The fish were on the sounder but we could not raise them, but had a ball with the plastics fished deep.
Not big fish, 6-20kg, but all in 10-14m of water and we could not raise them to the top.
Going back in Oct armed with a big collection of paddle tails - I have a bunch of 9-12 inch models I use on snapper and am currently making my own jig heads on 11/0 Jobu hooks.
I have made up of big flies for snapper with size 2,3 and 4 sinker sized eyes on 8/0 fly hooks, so the bigger jigs wont be a problem.
I use the bigger (10/0) size jig heads for reds, but I doubt any of these will withstand PE10 pressures.