Back in the days when I fished conventional tournaments - and even some that I've fished more recently - the key to getting a spawning bass to eat was to present the lure in the most delicate way possible and keep it near the fish as long as possible. These "finesse" tactics can be applied to fly fishing as well.
The key is small and near-weightless flies, and longer leaders 8 to 9 feet. I leave the 8-weight at home and bring a 6-weight outfit. That might seem a bit light for battling a big bass. But before you can battle the fish, you need to get it to eat. Spawning bass are exceptionally spooky! Light tackle and finesse flies are the ticket.
As for the fluke, nothing matches it better than the gold standard of freshwater fly fishing, the Woolybugger!
In tying woolybuggers for bass, I make them larger than those for trout, usually sizes 4 down to 8. My SR71 Woolybugger has proven to be a real killer, with the action of the schlapplen feather too much for Miss Bigmouth to handle. But any type woolybugger will do, and in fact, the 5.36 pounder pictured above fell for an olive Fluff Butt. A Fluff Butt is nothing more than a woolybugger without the hackle, right?
Remember that these spawning bass are replenishing the waters you're fishing. So handle them gently and release them to lay their eggs.