Large outposts aren't worth it, prestige cost is too high
There is no reason for prestige points to be 6 times higher on a large outpost than on a small. Sure, you have more room to get more kills, but less people play large outposts if there are medium or small outposts available. Add in how much longer it takes to build a large outpost and you end up spending more time to make something less people will engage with that is inherently harder to maintain.
Also just realized that size is not taken into account regarding ranking or reward; you lose the same amount of rank per death on a large base as a small.
Given prestige implies a large base is supposed to get 6 times the kills, the game design ACTIVELY DISCOURAGES Raiders playing for progression from choosing large bases.
There needs to be additional incentive to play a large base.