I tried The Rotted One + Over the Line + An Empire Reborn 🙂 I could make epic wins but performance wasn't great (in my case).
Less aggro scenarios with An Empire Reborn can be potentially competitive. Like, casting it on Netherswarm Lord to get 2 that will buff each other at the end of turn - this alone makes AER worth having in a zombie deck.
Having one or two Bone Rollers is interesting too. If you tempt-fate ward for a crowd of zombies+, Magic can do nothing and usually loses. At the same time, when you cast AER, you get 2 blitz Bone Rollers ready to attack enemy creatures (although you won't have their Roar, of course). AER also can turn an enemy buffed creature into 2 basic copies which can be useful in case of Nature/War buffers. So, unlike Over the Line, you can use it for taking control of the board.
This is my last version, just a zombie deck with AER and Necronomics (I should add one more big creature - what I have isn't enough for AER):
With Necronomics, you can drop a Rhino and cast AER on it on turn 4 + pip, for example. Or you can drop Obelisks and, then, add a Necroscepter on turn 3 + pip.
I like it but agree with your self-critiques. To that, I'd add that I think OTL is the more valuable card. If I decide to drop a card, it would be 1x AER before I dropped 1x OTL. 2 creatures on board can still be slept or ordered or stalled with frontline. OTL is an excellent finisher because it avoids this. AER is a nice supportive/flavor spell.