Dudes and dudettes, I think he’s asking how does the FT get under there in the first place, not necessarily how to deal with them, as he wants to trap the point of entry.
But yes, whenever you encounter these little campy bois, just plasma. It might take awhile because they could be stacking Supports with medkits and plasma splash damage isn’t the same anymore, but just remember their resources are finite, yours aren’t. Its a game of patience with those people.
Side note, we got a Pred stuck in there once, it was the funniest shit. I think it was a little baby Scout, I was doing the mission and he came around those huts and had an engagement with my team, and when I finally got over there he was stuck underneath there somehow and we all lit him up while he was panicking trying to get out. We downed him but were unable to get his mask off cuz he was far back at a weird angle, and he sat there watching us trying to shoot through the wood. I was using the SAWZ so eventually I found a spot where I could get it, then he hit the self destruct lol