I haven't dealt with this raid yet in my plains base a ways away from mistlands. Structure wise I imagine using the hoe to create a earthen wall topped with stone extending outwards might work since I imagine they aren't like Drake or Bats but start spawned on the ground.

Otherwise you could maybe create an earthen wall in the shape of a U that is thin enough for the player to deal with 1 enemy at a time at least when it comes to seekers. Soldiers (if they spawn - again I haven't had the raid yet) you probably want to have an elevated earthen pillar to stand on top of and use ranged attacks or the iron sledge / other weapons to whittle him down while keeping an eye on seekers.

I am curious about the max number of enemies that spawn in waves though. Perhaps 1 soldier and 4 seekers?