65 lb test is fine as is 50 the reasoning behind using 80 to 100 lb line isn't for the fish but the lures. When casting them if you get a backlash or as we call them a professional over run. the 65 lb will still break and at 25 bucks a pop on average thats an expensive breakage when you could save it by using atleast 80 lb.
As for using 65 lb on Gbay feel free if you don't get backlashes you won't have any issues.