Battery Eliminator, Aerodyne's design.

[Aerodyne]

I guess it's ready for 'set' testing now, Mark - if you haven't already tried it, that is. Agreed a crowbar on each LT line is a reasonable precaution even though the regulator has a built-in shutdown. A zener after a close-rated fuse in a line should provide a simple but effective trip, or you could go for a thyristor type. I believe the lowest zener is about 2.1V but that would still be OK for your 1.4V supply, I consider.
-Tony