When you hook something big on UL the fish has such little resistance that they all just seem to run your drag like a catfish......I've caught 8 lb redfish on crappie rods and they dont fight like they do on heavier tackle, they just peel drag on the bottom as long as they can.....Theres pretty much no way to know for sure.

But if your serious about getting some serious toads I would upgrade from UL. Theres a compromise to be had if you dont like heavy heavy stuff. I usually fish 6'6 spinning rods when using smaller plastics or small jerkbaits and I only use 10 lb test. On baitcast, I generall use 15. They still fight, still fun, and you dont snap fish off all the time...

Good luck

Also, I learned from a friend recently to not fish senkos with 5 lb test in heavy timber lol rusty spoons