Interesting read that's full of geek-speak:
Aggregate Data On PS4 Internet Usage : PS4
Longest story shortest, an hour of game play will use 30-200mb of data which is likely more than web browsing but less than playing videos online.
All of the above is correct- campground wifi generally sucks. You might be able to get a 4G/LTE hotspot, something like this (each carrier has different options):
AT&T Unite - Mobile Hotspot from AT&T
You'll just have to watch usage depending on what data plan that you sign up for.
And, the speed of your actual cellular internet will affect your multi-player gaming experience. It's hard to say if a cellular internet connection is fast enough for the micro-bursts of messages that online gaming is.