jumped back into my old unreal portal project and fixed it up to use the newer DynamicMeshComponent instead of ProceduralMeshComponent to cut holes in walls for collisions, which is much faster and less fucked up. plus it means the holes are portal shaped now instead of secretly squares.
the problem this solves is, when you place a portal on a wall, then try to walk through it, you hit the wall. so i'm disabling collision on the wall, making an invisible copy of the wall, cutting a hole in that, and letting that be the collision for the wall with the portal on it until you remove the portal. p cool