I have a couple of thoughts....
I suspect it's a Brown you're after, no?
The only tactic I'd change is go with a heavier leader/tippet, possibly one no longer than 4'. From what I see, the water appears somewhat turbid. Then I'd hit the hole an hour or so before the official sunrise. There's a real good chance that that he'll be out of his sancturary and in his established feeding lane.
Be patient and look for rythmic bulges and try to position the fly a foot or so up from them. When you strike, do so in the same direction he turns, chances are he'll turn in the opposite direction in an attempt to get away from the pressure. There's also a very good chance he'll come right at ya' after he makes his turn. So, don't try to play off the reel, strip line in, then fight from the reel when you have a little more room. Oh, and try to keep the rod low, playing a brute in tight quarters in the "classic" rod high, butt close to the chest only forces him to try and go deeper. I also wouldn't try to get any closer than 25-30'.
A "trick" I learned years ago when Steelheading, is to strum the line like a geetar they will turn and it's worked for me on Browns, 'Bows, Salmon, and nearly any other kind of fish I've played...
Failing that, if it's legal, I'd suggest doing a littl night fishing, using the same approach I've described.
Out here, fishing for trout at night is prohibited, no earlier than an hour before the official sunrise and no later than an hour after the officel sunset. Biggest Browns I've landed have always been within an hour before sunrise upto and mebbe an hour after the official sunrise, depending on how deep in the woods I am...Good luck and it can be done. FWIW.