[gen 9] Best method for hunting double marked shiny Pokémon in gen 9?

Hey everyone! For the past few days, I've been trying to get a double-marked Gen 9 Shiny Pokémon to ribbon master, but I feel like I can't really land on an exact method for doing so effectively. Currently, I'm hunting shiny flutter mane using sparkling, encounter, and title power, as you can't combine humungous/teeny with encounter with any recipe in the game. So far, I've yielded plenty, and I mean plenty of shiny flutter manes, even some with some cool marks, but none are teeny or big enough for the respective size marks. I've also tried mass outbreaks for non-paradox Pokémonn like frigibax near that big ice mountain or mimikyu near the big crystal spring in kitikami. From what I've experienced, using sparkling, humungous/teeny, and title power seemed like the obvious choice since so many of the Pokémon are spawning because of the outbreak, but every time I do so, I get shinies way less than I would've expected, and most do come with some form of a mark, but no luck on double marks. Using the same recipe I mentioned earlier with encounter power, yields nonstop mass outbreak Pokémon and way more shinies, but also most of them are duds that sometimes don't even have marks on them. I guess I'm just kinda at a loss at what the best method truly is, and was hoping that someone here could give me some advice on the best method to finally obtain a double-marked shiny. Thanks for reading, and I hope this makes sense.