If you have a lure rod, I would scout the area with that first.
Duo/IMA Nabarone 125 in colour 012 is a great lure.
As are Duo Tide Minnow 140 in similar foiled or ghost Sandeel colour.
Savage Gear Horny Hering (designed specifically for seatrout)
Or, small metals - Dexter's, twisties or Duo Press Bait or Kamuy.
Catching sea trout on the coast is really hard going, and I would personally wish to be on a spot that is really productive before trying with fly.
I fish an area which is heavy in decent sea trout numbers and I have only caught one and lost two in many hours of casting for bass, or casting specifically at present sea trout.
They are damn hard to catch, even when they are there.
Mind you, my local spots are open coast. I suspect they are possibly much easier on eastuary mouths.
Still, I would be chucking lures first. Much easier to scout the area, find marks, assess likely tides, etc., purely because you are a lot more mobile and can cast much better distances.