When you're travelling on the open highway, be mindful you are not the only ones out there and some people make a living driving every day.
Most people don't like being interrupted or inconvenienced at work and that also applies to truck drivers. When you're on the highways regularly check your mirrors at least every 60 seconds. It's surprising how much distance someone can catch you up in that time.
If you're going to be on the road for quite a while a UHF radio is a great investment. By monitoring channel 40 you can converse with truck drivers and help them get around you. Be mindful this is a truck/semi/roadtrain drivers' channel so random conversations with others are not appropriate.
Maintain your speed. The truck driver will sit behind you and pull out when they can see its safe for them to do so. They will know at your speed how long and how far it's going to take them to overtake you. Once they begin to overtake, you slowing down is going to make it safer for all parties.
Once the truck has safely passed give your headlights a couple of long one-second flashes to indicate they can come back into the left hand lane.
If you use a shared rest stop, pull over to one side so trucks can easily drive through. If you see a driver walking around their truck/semi/roadtrain, say g'day as most appreciate a chat. If you have the kettle on, offer them a cuppa but if the truck is locked up and the driver sleeping do not disturb them. This applies to running generators while a driver is trying to sleep. Just remember, you're on holiday and they are working.