Mifi & Booster Aerial

Hi all -

I recently purchased a camper van and am trying to work out my best option for internet. What I think is going to be best is using a 12v powered Mifi box and connecting it to an external booster aerial - does anyone have recommendations?

Then I was wondering if there's a way to have the aerial booster connect to a phone so the tethering off that can be used - so for example let's say I have 4GB left on my tethering plan then i might as well use that - can the external aerial run to a port that a phone can be connected to instead of the mifi box - just the option to choose would be nice.

Cheers!