Agree with Keith. sounds like a very dodgy operation and if not a registered transportation business then you dont have a leg to stand on if van gets nicked, burnt, seized by customs etc which will more likely happen soon if the same vehicle keeps crossing borders. Although good intentions are meant, you never know when some drug, smuggler, terrorist could abuse this facebook offer and no matter how much you check the packages, would you bet your freedom on it?
Use a proper legal transportation company and those ones that make the offer to take stuff...think again, after all you wouldnt take a package through the airport if some person you hardly knew gave it to you for transportation.