Those camps / garrisons could be a random spawn, in different zones, with stunning views, that You could queue for like for an arena and folks could watch from the outside.
this could be a server event / tournament with leader boards: the last man standing
prizes and titles included
admission fee: azoth salt / gold as a revenue stream for less contested settlements
fOMO: only in certain days, last week of the month, etc.
I think the issue is more that there is no ranked pvp. This needs to come first. Once it does these things will stop existing. Also i think we should just increase 3v3 to 5v5. I believe all content should be either 5v5, or 10v10 with the exception of invasions, and wars, which should be capped at 20v20.