Here's a thought, make your own party, build it with diversity there's like 9 jobs in the game so why try to force an illogical group comp and make your life easier. That way you create a more positive group experience and you can get what you want hassle free without all these shenanigans. Also it doesn't take a rocket scientist worth of gear to clear these fights in the average gear it says as more often than not you will have overly geared people in other groups to do some more of the heavy lifting. The only fight in the entire dungeon where its not all in the same area is the trash hallway before Thanatos. Stay on your platforms and you will be fine.