As A 4 Wheeler, How Do You Communicate With Trucks?

Sometimes a trucker does me a good turn or whatever, how do I say thank you? I've had truckers hold back traffic for me, and stuff like that, I'd like to know if there is some way to say thanks. Also are there other ways to communicate, like when i am holding back traffic for a truck, how can i say, all clear?

A friendly wave and smile to say thanks. Using your hand to wave the truck towards its destination when you're holding back for them to go. Same things you'd do for another car, biker, or pedestrian. Just make the gesture is bigger so you can be seen well enough or roll down your window and do the hand gesture that way.

If you catch a driver needing in and are going to back off to open a lane, one thing you can do is to give your high beams a quick couple flashes to let them know they have enough room to safely move over.