Wooly Bugged has at least one video on fishing the Elkhorn. There are RR tracks that parallel at least a portion of it's length, with multiple very old steel truss bridges as a clue as to what section he's fishing.
As far as the BIG browns in some of the HFA videos, I think it might be possible, due to it's length (24 miles), that Jonathan is fishing more out of the way sections of the EH? Just a guess.
I know there would be a lot involved in getting there and fishing the EH, basically because it can't be a one day trip from Pa, and lodging might be a problem, but I'd love to somehow experience fishing that creek, given the history of it's trout population.