Chad XFit

Hi All, My first post here...been lurkin for awhile...awesome place...hope I can contribute. I was just wondering what some of you are using when using deep diving crankbaits, 15-20 feet...I hear some saying use lighter line to make it go deep but what I find is that when that deep thats quite a bit of pull on my line...if I got hit by a big one it seems it would break the line quick. Heck, it feels like a big ones on the line just pulling that crankbait. (I fish back of boat mainly btw...so reeling plus a slow troll as well) I feel like maybe going with a 7'6 pole and some thicker line, maybe 20 lbs.... Just wanted to see if I can get some input before buying the new pole and any tips... Thanks much