Sorry to hear of your unwanted visitors. They can certainly destroy a lot of hard work and $.
We live on the edge of the woods and have a perennial stream of mice vermin trying to invade our house and vehicles. I have found that the best offence is a strong defense. If they are getting into the truck, you obviously have a gap/opening somewhere. Find that breach and devise a method to make a durable barrier. Easier said than done, but it is possible.
