I usually don’t fish down stream. There are exemptions to every rule. This trout was caught fishing downstream under all that CRAZY cover. What would you use and how would you battle the trout?
Firstly, nice fish! secondly I would use a harpoon and steel cable! 
All the best.
Mike.
Mouse presented downstream on 0X tippet. And a looooooonnnnnnng handled net.
I would use what you did!
Nice catch:D
Is there any activity visible from food sources? Are there any bugs about? Terrestrials? Minnows schooling nearby? Failing all else, how about an olive woolly bugger with a bit of added color. Maybe a whisp of red maribou added to the tail and yellow hackle palmered. I’d probably use a heavy tippet and drift the fly with very small bounces. Then I’d move over and let Warren catch the darned thing. 
Ed