Unlimited data hotspot for 18 days

Hi everyone and thank you very much to whoever will be able to help.

We are a family of 6 (2grandparents, 2parents, 2 teenagers) visiting from Europe for 18 days next month, in the California-Nevada-Utah-Arizona parks area, which we will be traveling in an RV.

I am looking - if it exists - for an unlimited hotspot data plan to be used with a hotspot device that I'm happy to buy along with the sim card locally, because I think the European devices wouldn't be compatible with USA sim cards.

If not unlimited, then with a very large data consumption (IE 100gb) and that wouldn't need to be renewed after our trip. 

Also happy to buy 2 sim card to add up the data plans, if unlimited or very large data plans are not an option.

Thank you for your help