I work on/install signs and it's not unusual to be 100'+ on a JGL or crane, I even serviced the 1st National sign in St Paul once at my last job.
It's a mere 500' or so to the top. But at least you are on top of something solid feeling. It looks more scarey from the ground than it is. On top its like this:
So you are really only gonna fall about 50' but try and tell that to your stomach!
I'm crazy, I know.
But as Nosmo said It's not the height or the fall that is scarey its the sudden stop at the end. which brings me to the next point: why no plan B? I.E. people base jump of of stuff like that all the time! Wouldn't you think having a chute with would be worth the extra weight?