first task is to see if the site has wifi (free or paid for) as this will be the best (and maybe the only) option
if not then he is probably going to need a 4G signal so check if its available and if you have the correct provider for it
then it may be a case of trying wifi dongles or setting up a router of some sort in the caravan that can handle the camp wifi or the 4g dongle
I doubt it will work just plugging in a usb device into the mag but there may be some compatible usb dongles or wifi adapters out there that may work if the mag has android drivers for the devices ?
maybe the mag has built in wifi ? in which case it needs to be able to log into the camp wifi system (if available)
so start with an internet source and work backwards to the caravan and mag, solving each technical issue as it comes up
so the first task is to get the mag onto the internet , not iptv (iptv comes last)