Buy a cheap canister/pump type bug sprayer like the exterminator might use, fill with 1/2 water and 1/2 lysol and a box of baking soda, and spray the dirt, and the underside of anywhere he might have sprayed. Then throw mothballs all around under there. The strong mothball odor lingers and it is too strong for most cats to tolerate. Get a dog to pee all around outside the trailer....that helps keep them away.
