I Frequently make tuna set ups for customers who want to chase Yellow Fin Tuna, here is my rigging. Very large capacity reel such as a Tibor Gulf Stream or Pacific, on the Gulf Stream I start with 550yds 0f 30lb braid then attach that with a bimini to bimini loop (looped through twice) to 150yds of 50lb braid (this part of the backing takes the biggest beating thus the higher test) then a bimini loop in the 50lb. The braid is cross hatched onto the reel so it does not cut down into its self and potentially break. I use Rio Leviathan 500 grain sinking fly line. I make a loop in backing end of the fly line by looping it over and securing the loop with three or four nail knots made with 17.6lb Rio hard mono. The backing bimini is then looped twice through this. I make a Collins Loop at the end of the fly line with 22 pound hard mono which gives me a 40 lb leader loop. Stripping gloves are a must and yes DO NOT TOUCH THE BACKING!! As you can see everything is designed with a much higher break point than your leader potentially saving some very expensive stuff! All this goes on a 16wt rod such as a TFO Blue Water HD rod. About $1,250 all together but, if you want to beat a yellow fin ya gotta have the right stuff!