Most Plecs live in colonies. Granted, in the wild they have the option of escaping aggression.
Unfortunately the same rules apply to the very expensive fancy plecs as well.
"you've got to fight for the right to party"
One cave- you are setting up a breeding situation not a holiday park.
You can have lots of hidey holes with a jumble of wood and rock.
Your dominant male will take over the cave- he probably will but not necessarily be the biggest. yes expect some scrapping between the males at this point- the greatest chance of fatality is if dominant male traps a younger male in the cave.
Once this is sorted extract the other males, and just leave the cave ,but I leave a little stack over and around cave for females as they will loiter around there then.
With one cave you can probably sort all this out in a day-then start your seasoning programme.
I use tiny little eheim pumps ( 200-300 ltr/hr) to blow across face of my bamboo or ceramic cave -about 15cm I guess from cave, and not into cave. I do this for aeration. With the tail out the male is actualy guiding a liitle current into the cave, and then fanning with fins.