If you can swing a spare phone, no need for a hotspot and plenty of apps to use. I currently use 'Dog Monitor' Which allows video and sound. Also use Valarm to track temp with a remote sensor but it's a bit more involved to set-up. What I do like about Valarm is the ability to text/email when temp is out of range or sound (barking) is recorded. Between the two apps, I'm pretty comfortable with the dogs in camper and know I can peek at them anytime.
Would work with any data plan and I've never experienced much data use. Video is only using data when active.