My preferred way to play is shattered world counties. Issue is Tribals usually take over the map because of the conquest Casus belli. I have been remediating this with the Shattered Worlds mod only for its "advanced ai" gamerule. I use MGRs Alternate world settings to actually shatter. Anyhow the issue with that rule is about 100 years in it just becomes a free for all.
Would it be possible to add a game rule that adds the conquest to every ruler (One mod already does: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3399293199&searchtext=shatter) and then another for it to turn off for the governments that should not have it in say 50,75 or 100 years? If you ever played CK2 HIP shattered they had a similar function. Man what a blast. Every single game different.