The thing is that removing the screamer and/or replacing it with wandering hordes would make your base an absolute safe space. Yes, wandering hordes might spawn when you are at your base, but that won´t happen too often. Unless they are way more frequently than now, but then your problem stays the same, you will still get hordes when doing quests.
That said, a rework of the mechanic couldn´t hurt. Right now a moat, 1 deep and 3 wide filled with spikes and no windows on the ground floor is enough to make sure you only get a screamer horde when you are unlucky entering/leaving the base or repairing the spikes. In theory it´s possible to never get a screamer horde at home ever if you want to go all the way for home safety. Make a tunnel entrance that you enter outside of the screamer spawn zone And if you need to repair spikes you turn off the heat sources.
Snow/Wasteland infestation quests and a screamer or two showing up are fun though.