Dear god no. I don’t mean this as an insult to you, it’s cool that you’re thinking of ideas, but this is an awful suggestion, for multiple reasons.
One of the reasons they changed the purge mechanic to be controlled by players is that the large majority of people hated having their bases attacked semi-randomly and without them being able to have any real influence.
In addition to the above, this idea punishes people for building near the edges of the map, which is already a slightly more difficult place to have a base (and by “difficult” I mean it takes more time to travel to most of the places on the map, so being near the edge is already more time consuming than building in the middle), there’s no reason to make having a base near the edges any harder than it already is. If anything, attack should come from the dead center of the map - of course that doesn’t make any sense either, again people disliked the old purge system.
You just need to do more purges, and don’t worry about what other players do or don’t do.
The whole point of PvE (for most people) is that they get to choose how much they want to interact with other players, a lot, a little or none at all. Each tribe is an island unto itself, unless they voluntarily choose to cooperate with other tribes, anything the forces inter-tribe cooperation, and especially across an entire server, would make most PvE players quite unhappy. People play PvE because they want to interact vs.E-environment, not vs.P-players.
This game, like most survival games, already requires a bunch of farming. Being required to farm just to keep your base alive would be pretty insulting, they already have the decay mechanic for that.
In the end, this sounds like you’re a player with a lot of extra time on your hands, not everyone has that much time to constantly defend their base or farm for bribes, that’s why many people play PvE in the first place. Time is valuable, this idea steal waaaay too much time from people.