When you are all alone in the truck it is quite obvious that you would feel alone. Though you could manage to play some music in the truck it would not be a true companion for you. It would just be an entertainment for you. If you have the habit of growing pets at home then you could surely get them in the truck along with you so that they do all sorts of funny things when they are placed in the truck. You never have to confine them to the back seat from which they are likely to keep their tongue outside without having to say a word. Also, the other travelers on the road would look at it and would continue to talk about it which you may not like. Also, how it feels each time a traveler crosses your truck is something that would be distracting your attention on driving the truck. This is where you should be able to understand the fact that having your pets in the front seat would be most convenient for you.
So, get the dog seat covers for trucks so that you could let them sit anywhere they are comfortable with. You could also make them enjoy the ride along with you so that there is nothing much that you could hide from them. If you deny them to accompany you in one ride, they are likely to behave in an annoying way. Once you accompany your pets with you and then they feel exciting then you could plan to buy the pet covers. Of course, you need them even for a one time ride as you never know how the pets would react when they are inside of the trucks than letting them move around like you usually do when you are at home.