I went up this time last year and had pretty good success. Unfortunately aside from the evening worm fishing, the ONLY thing that was getting fish was a very small chrono in light brown. It was the most amazing thing. We were anchored 40' away from another boat in a bay and the other guys were nailing one after another. Not a word of a lie they had to have got 30 fish and we didn't get a single hit. We were using the exact same chronimid but in a slightly larger size and got skunked. That night I wandered up to their trailer and asked them what they were using and the guy gave me 2 chronimids that they were using. The next day we landed 18. The web site
http://www.tunkwalakeresort.com/fishingreport.php has a very informative fishing report including photo's of the flies that are working.
I have also skipped over to Leighton when things on Tunkwa have been too slow or busy.....some big buggers in Leighton if you can get them to bite!
Have a GREAT trip!