I think the multichannel SACDs use the same mix as the Perception box DVD-As, so you may be out of luck. Have you listened to the Atmos mixes on the streaming services?
I was checking Discogs this morning, and figured out that you can filter artists and albums by Multichannel versions, which makes it SO much easier to sort this all out! And yeah, it looks like the SACDs also used the 40th Anniversary mixes. As far as I can tell, the only time they ever released a non-40th 5.1 mix was the original DVD-A of L.A. Woman from 2000, so I just snagged that one for now.
(I'm also seeing reviews of the Perception box that note, understandably, that the 5.1 versions of the earlier Doors albums don't have much of a multichannel effect anyway, since there wasn't a whole lot going on with the original master tapes back then. I figure I'll just work my way backward one album at a time. If I like L.A. Woman enough, I'll consider getting Morrison Hotel, and if I like that one, etc etc.)
Yes, I've heard the Atmos mixes, but for reasons not worth getting into here, I find it much preferable and easier to play multichannel content via dedicated discs (even though I do actually own an Apple TV 4K).