What if you help out Rusty a little around his house/barn? In the barn you swipe the floor clean from any dirt, dust and hay. Clean and tidy up his equipment. Maybe sharpen and clean some tools. Or maybe you clean his car and truck. Let's say you know about his "nightly activities" but he'd rather not have you see the horrors of the scenarios so he discreetly warns you before hand.
It's nice for someone to clean up the house while he's out & about doing Trucker things & other "activities". Rusty isn't home most of the time because he's always on the road, but coming home to a clean house & barn puts him at ease.
Rusty isn't much of a cleaner after he finally gets home. Honestly, all he wants to do is go to bed & hibernate. His back hurts from driving all day & night; that man wants to sleep in his comfy bed & pass out for hours. When he wakes up, he probably isn't going to leave the bed for another 5 hours.
Now, the one place he will not let you clean & he would rather clean it himself is his truck & his car. He doesn't want you involved in his "work". It's his business & his business alone. Rusty doesn't want you to worry about him too much.