agesilaus wrote:
Seal up the doors and windows and stick a garden hose in the vent and fill the camper with water. Let it sit a day or so and drain.
BTW places have exploded from too much bug bombs.
You have to add a cup of Dawn dish soap. Spiders are quite water resistant due their coating of hair trapping a layer of air around them. This helps them float and enables them to breath for a time. Being small they also use little oxygen meaning it takes awhile for them drown. The dish soap defeats their water shedding defenses and drowns them in seconds.
By Baupi, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7273120