My boards are going into a container next week for shipping home to Australia. This could take up to eight weeks to complete. They will be stored inside board bags which will subsequently be wrapped up in export wrap.

I'm wondering about the vent plugs. My instinct is to take them out as I don't know what conditions they will be exposed to (though I'd bloody well hope they and the rest of my belongings are not exposed to high temps. The boards and bags are clean and dry.

Is there any reason form me to screw the vent plugs shut?

Yeah, unscrew the bolt. I normally do not, ie have left the bolt in my boards for years with no apparent ill effect but if I was getting them transported long distances I'd take the bolt out. My boards usually go into the bag still fairly wet and I think if I take out the bolt with the board wet then there is the chance moisture will get in while it sits in the bag.