LR Mobil & Desktop: Storing Images

Do you intend to use any other Lightroom apps apart from LrMobile on your iPad? If you are going to be iPad-only then I'm struggling to see how it will all work. What camera will you be using - iPad, phone or dedicated camera? If the latter, in order to edit using LrM on the iPad you would first need to import them into the app. Once inside LrM it will want to upload them all to the Adobe cloud if you have an internet connection, though you can pause that if that's not what you want. You could also use the Files app on the iPad to copy the images from the camera to an external drive (but no edits of course).

When you arrive back at your desktop, then what? Connecting the iPad to Wifi in order to do what? You would have no visibility of the images and edits contained within the LrM app, so the only way to get the (unedited) original images to your RAID would indeed be by connecting the external and copying them from there. You could then rename them as you do, but they would then no longer be any form of backup as the names would not match the filenames of the originals within LrM (there is no rename capability in LrM). An alternative option would be to export as DNG from the iPad, using AirDrop to export directly to your desktop (those DNGs would contain the edit information, so would be a much more useful backup), then copy from the desktop to the RAID. You'd still have the rename problem to address,

Without using some other app such as the Lightroom Desktop app or even LrClassic, I really don't see how this can work. Most travelling iPad users that I know will let the originals upload to the cloud as intended, and once in the cloud they then have a few more options, but the only one that allows you to rename the originals and create a backup on your RAID automatically would be using LrClassic. Briefly, the images upload from the iPad to the cloud, and from there they download into LrClassic (and you could set things up so that they are automatically stored on the RAID when downloding from the cloud). You can then rename the images using Classic, and that rename would sync up to the images in the cloud.

You then have further options such as removing the originals from the cloud to free up space there (after safe download into Classic), then resync them back from Classic to the cloud (as much smaller smart previews). Many users use this last workflow....