I too use my iphone’s Personal hot spot to get local maps to my non cell iPad and it’s not a pain at all. Once it’s set up the link is automatically established whenever both devices are on and near each other.
It is NOT necessary to turn off the hotspot on the phone between uses. Unless the link is in use, battery and data consumption is minimal to non existent.
Even when the link is established due to proximity, if the DJI app is off, no data is being transferred. In such cases, my IPad will select and use a faster WiFi link if available, leaving the hotspot un used for email, browsing etc.. Effortless and transparent.
In any case, once maps for a given location are uploaded to the iPad, they are stored in its cache memory and are there to use in flight even if there’s no link to the web at all.