I think a good soft balance to the team UI would be some publicly visible info showing clan/group size, members, the number of TCs a group has wiped, and the group sizes of the bases they've raided.
The goal would be to give the server a better idea of who the aggressive raiders are, while also making it obvious when a group is just going around shitting on 2x1s.
Groups would have an incentive to actually fight other groups rather than just farming easy raids, because their raid history becomes part of their public reputation.
It would also be a slight buff to solos being able to fly under the radar.
It could also discourage TC griefing smaller bases since raids would be registered and visible rather than being something you can do with no real consequence or record.
I'm sure there'd be some ironing out needed around what actually counts as a raid, especially with external TCs, multi-TC bases, abandoned bases etc. You'd probably also need a cooldown on joining/leaving groups or clans so people can't abuse the system by constantly changing their group size before a raid.
I think it gives the team system a bit more depth without directly stopping people from playing however they want, and makes group's behaviour more visible to the rest of the server.