I would'nt use anything over 10 lb mono, or 12 pound Stren Magna Thin. I also have used braid up to 30 pound and seems to get the baits deep enough. I use the same rods I carp/channel catfish with and they all have 12 pound Magna Thin or 30 pound Power Pro. If I were going to dedicate rods specifically to trolling cranks Id use 8 pound mono or 15 pound braid. I also use my jigging pole with 6 pound mono but thats pretty light if you hit a snag.
"In my father's house are many mansions..." John 14:2