Super reasonable.
I agree with he part about concentration. IMO, it is clear RAW and RAI that you can keep concentration up through a rest and regain slots, and I can't see any RAW based arguement against the "KO a hexed critter and then short rest" part that people object to.
I agree that something has to happen between rests, too.
I have a question about that, though. What about this scenario:
Party has reached level 5, leveled up, is on an adventure in the wilds.
First thing in the am, the warlock and ranger go out to hunt down some food for the next few days or later that day, whatever.
Warlock and his familiar bag a rabbit, right off, ranger and his per bag a small deer.
Warlock uses Hex, because he knows he will have full spell power back after he and the ranger cook their spoils and salt them for storage or whatever (a short rest IMO can definately include cooking some food).
Finds that the spell is more powerful than before, and will last all day. Does his thing, rests, and finds that his full spell power returns to him, and Hex is still going.
Now, is this a problem? What if hunting and checking traps have been part of the routine anyway, before this?
Certainly a warlock with a predator familiar, like a bird of prey, will be a great hunter of small game, so why not?
Does making and eating breakfast need to be part of a long rest? I've never thought of it as such.
Just curious.