I have personally performed this exercise once...it took 3 days.
00 F250, rockers were about 12" high, they were also suprisingly thick / strong.
May be different of different trucks, rockers, etc.
Ended up with a torch, heat gun, vice grips and lots of time. It was an absolute nightmare! At one point, I drilled a hole in a portion I had pulled off the truck, hooked it to a come-a-long and tried to ratchet it off...hole pulled through. Once I pulled the rocker cover off enough to bend it against the curve of the rocker that is when the trouble started.
I have debadged nearly everything I have ever owned..I would not do rockers again. My paint was fine, needed a good bit of polishing and only had a few uh ohs.
Hope this helps. Before / after attached.