We didn't get any doggies by popping but the other groups have found them in the same areas as the GTs. So you should be OK.
Also for jigging the boat didn't need to find fish on the sounder, they just found a depth of +/-100m off the drop off then drift along. Found plenty of fish this way.
Take a light outfit as well as there are a lot of good bluefins and other trevallies in the surf if the GTs won't eat.