Once your iPhone is out of range, the camera won’t be able to connect to the hotspot.
I have used 2 different methods.
1. I had an old phone to use as “the camera”, I downloaded the Alfred app to my current phone and the old phone. I made sure to keep the old phone plugged in at all times and propped it up so I would have a good view of the living area of the camper. The old phone would connect to Disney’s wifi. I was able to use my current phone to see what was happening in the camper by opening the Alfred app and watching what the old phone was capturing on the camera.
2. I did as Scarletfire mentioned and got a travel router which I connected to the Disney wifi (this was achieved using the router’s app on my phone or laptop). I used that router to create my own secure WiFi network and then connected a camera to the secure router wifi network.