If the fish aren't even looking you will have to try the crab just to be sure they are fussy and skittish before getting serious about stealth. Be sure to be poling or sculling and the motor is up. Or . . . drift the side of bars in ten feet of water with the current casting to the skinny water and retrieving as deeply as possible. Or . . . go take a look up to five miles off shore just to be sure there isn't twenty acres of boiling water with feeding stripers in it. Learn to watch the birds.
Gulls scare the bait and the bass down from a blitz much more quickly than do terns.
Given the choice on the horizon, go for the terns. Cast there quickly to put your fly on a fish or at least into a group of bait. There were fish feeding here recently. Learn to spot a flicker in the sky at the limit of your vision. Could be 200 terns wheeling an diving.