Lots of data

I would look to a source such as rvmobileinternet.com .a group that reviews sources and equipment to do what you want. In your case since you NEED data I would pay for the annual membership to get the latest on what’s available.Just know that you should have Multiple plans ,at least 2 to provide redundancy. There are resellers who you can get unlimited hotspots from but they come and go and knowing what’s the latest is important to maintain connectivity. It’s a complicated space and sites like theirs have saved me a couple times.
Forget campground WiFi it’s very unreliable and for now that leaves cellular hotspots. We have 2 but all are grandfather/ no longer available so no reason going into them.