For weight, just assume as much as you can toss, as you probably will lose it on the retreive. Most guys will use a smaller diameter leader, often tying in a knot for a weak spot. One of the more sucessive guys I saw down there was using a heavy main line and a rail road spike. They would lob it out there just a short distance and get it to lock up on the bottem. They would then crank the rod down like a down rigger rod. The drop line they were using was very weak, and when a fish would hit it would pop the drop line and the rod would snap back, hooking the fish.