CASA can pay for it the bastards!
Get a grip. If you're flying by yourself, we couldn't care less what you do or don't have when your beloved tablet rolls over and dies. But if you have fare-paying pax or are mixing it with aeroplanes carrying fare-paying pax, then accept the fact that you need a backup for your Chinese-made consumer gadget with potentially untested software. Do you ever wonder why airliners cost so much, and how cheap they'd be if they were made in the same factory, to the same standards, as your ipad?? It's because they and their software are built to a standard 10+ times higher so they don't fail, and if they do there's multiple backup layers.
Quite frankly, if you don't have a backup of some kind, you're a fool and a menace to the rest of us you share the sky with.
Use paper backup or get a second gizmo. Simple.