Looks a bit like some of the tidal rivers & creeks I fish. Similar depth too. I'll usually use a floating line. Sinking is not really needed, but since it's tidal (with the currents) & there are deeper places that I'll fish for Striped bass, I also have sinking lines for my 6 wt & heavier rods. All my lines are WF, even for my lighter 3 & 4 wt rods, but a DT line can be useful if you also trout fish, particularly with dry flies. I rarely do.
I make my own leaders. Most are no longer than 8 ft, and I use no less than 10 lb test and more often 15, if I'm bass fishing with my 6 wt. Panfishing I'll go lighter, but then I'll go lighter with the rod too.
IMO, there's no magic formula, and especially not that will fit all fishing situations. I like to use some heavily weighted flies, so the leader & tippet needs to be stouter than with lighter flies.
I also like big flies, (4"-8") and even bass fish with a 8, 9 or 10 wt, depending on where & how I want to fish. Makes pulling even a 2 lb bass out of heavy cover or snags much easier than with the 6 wt.
I treat bass fishing with flies the same as with conventional tackle. One size doesn't fit all!