[Pierre-Marie Baty]

Nope, save yourself a lot of pain.

Just use TraceHulls with head_hull instead of TraceLines.

TraceHulls are blocked by clip brushes and func_illusionaries, and they also have the size of a ducking player. They are perfect for testing a reachability from point A to point B, much better than firing a bunch of TraceLines to figure out whether there's room enough for a player to slip through.