First, I wouldn't bother to tell anyone about that fish until I had the fish caught. Second, I'd take a camera and a tailors tape, maybe even a scale. I'd probably get off the ledge way before I was ready to land the fish and that's what I'd do, land it, drag it to the shore with a heavy enough leader to get it done.
I don't keep any trout, even big ones. However I do keep salmon and have caught big fish. I'd never mess around trying to net a big fish, I see people trying to do it and usually it's pretty comical. Best way to land a big one is to 'land' it. Then if you want to scoop it with a net for weighing and to control it while you measure it, the net will be handy.
Third, I wouldn't bother to tell anyone about that fish until I had it caught