Colony beards all night, even after dark — which ventilation additions actually work?

Third summer in North Carolina and my strongest hive has taken up permanent residence on its own front porch. It's been humid and 33-35°C for a week, and I expected afternoon bearding — but this lot are still out there in a thick curtain at 11pm, and a decent beard remains at dawn. Setup: single deep plus two mediums, solid bottom board, entrance reducer off, telescoping cover. They're heavy with bees and there's a strong flow on, so I suspect they're also parked outside because it's standing-room-only inside with nectar everywhere. Before I buy gadgets: which ventilation changes genuinely help — screened bottom board, popsicle sticks under the cover, an upper entrance, slatted rack? And is all-night bearding ever a swarm tell, or purely climate control?