What does he wish he had in his truck?

You.

You, full stop, case closed, answered.

If he can't have that because you're home taking care of things, then the answer is family. Do you have kids? He wants them there with him.

He can't have them there with him because shippers don't like random kids in the truck? Common AF.

The next best thing is to just answer his calls. He knows what time you and the kids are sleeping. "He knows*. He's not going to call unless he needs someone to answer.

When he needs someone to answer, be that someone.

You can set your phone to DND at specific times of night, but you can also set specific phone numbers to get through that DND.

Answer when he calls. Whatever time it is. He won't wake you up if he doesn't need to.

But knowing that the entire reason I'm doing what I'm doing, the late nights, the grease and dirt, the minor injuries, the traffic, the roller grill hotdogs, the shippers who ordered something then act surprised that it showed up, all of it, knowing that if I need to vent and tell someone that this kinda sucks sometimes...I know, I know that my wife will answer that phone. I won't call unless I need it, but if I call, I need it.

Nod sleepily, say "uh-huh" and "wow that's crazy" if you have to because you're sleepy.

But answer the phone.

That got heavy. Sorry.

Short answer: a good headset and someone worth talking to on the other end of it. Even asking the question about what he needs sounds like you got half that covered. Research what headsets are useful, legal and safe to use. Get his input. Then get him the one he needs, and answer if he rings.