Hi GnA
We run a 4g pre paid Wi Fi Pro through a 3/4G antenna on the truck when travelling and we also have a separate antenna on the van when stationary in camp and we have found this to be a great combination. You can use your 6s as a hotspot but your range will be greatly improved if you run it through a cradle connected to an antenna and it will keep your phone powered.
Cheers
Merv