Thanks, think I’ll run in a Ciggy socket next to the WiFi and just un plug it in the week when we are not using the van,I was originally thinking of putting an extra USB socket beside it but in the end I've just connected it to an existing socket already in place a couple of feet below it, running the cable out of sight down to it. It's also easier to disconnect the MiFi from the USB socket end. Although the MiFi runs all the time on a trip I turn it off and disconnect it when we get back.
Incidentally I have ordered a couple of the straight coupling connections rather than the pigtails for the Wi-Fi antenna connection, looks like they’ll work fine and less cable to worry about