If they are using the truck for shelter, you are screwed. When they are sheltering, they chew up everything to make nests. This is where you may find insultation shredded and wires chewed up, maybe later or until corrosion sets in and ruins lots of things.
If they came in for food that was left in the truck, you may be able to stop it by getting rid of any food and excluding them.
The only way to deal with mice is to exclude them. Try to find any openings and and wrap them with exclusion material. If you can get your smallest finger in the hole, the mice can fit. They make things for this, but you probably want the ones made of copper wool instead of steel wool. And you have to find every opening and block it off with the material. steel wool will rust. Moth balls don't work. Anything that smells bad won't work, or it'll be so bad you won't want to be near it either. The ultrasonic things don't work. Once they are established you have to trap them or poison them. If you have animals ( cats or dogs ) you probably don't want to poison them. If you do use poison make sure you give your animals Vitamin K supplements as that is the antidote and it is safe.
If you place bait or traps or poison DO NOT PUT IT NEAR THE TRUCK. that just makes them use the truck. move it away so they don't associate the truck with food or safety.
My mice go to traps are a large bucket with a can, either aluminum or steel on a coat hanger like a log roll. Coat the can in peanut butter, and give a ramp up to the brim. The can should spin freely so if they reach out to get to it it spins and drops them in. Put a few drops of vegetable oil in the bucket to make it slippery. If you get a mouse, leave it in there. It crying for help will draw more in and they will also get trapped and draw more. Think you have "a mouse" you probably have 10,20 and a dozen pups somewhere.
Sticky traps work, but they learn and will only work a couple times before the mice learn to avoid them.
