try a number 6 ,1/32 on 6 lb mono maybe , use a fairly fat plastic and then cover the hook point with a nibble so its a little on the weedless side with NO hook point visible .
cast it and let it settle for a bit watch the line as it falls with lots of slack it in . try to see about how much line is going down and when you think you are close to the depth you want slowly raise the rod tip and reel very slowly .
it will take practice and you will lose a few jigs ,but once you master that free fall , you will likely ketch fish floating it along past the tops of the cover .
there are likely some better ways to present it but that's probably what I would do ….
we fished a spot like you are talking about years ago and ruined a bunch of fishes day letting a light jig fall on the opposite side of a submerged tree line and slow dragging them back across the tops of those trees on the old creek bed .
my 2 cents