Not sure if I'm misunderstanding something, but high ceilings aren't really a downside for Atmos. In fact they can be an upside as they may make it more difficult to localize sound coming from the height speakers. The Trinnov HT position guide recommends 3m as ceiling height and states that higher may be preferred. If you are willing to mount speakers to your ceiling, that should work just fine. The distance is only a factor insofar as you'll want those speakers to be powerful enough in terms of SPL.
The most important thing for tops is that the speakers should be pointed at the listening position, and the recommended angles need to be fairly steep -- from 55-90 degrees relative to listener position, depending on number and chosen layout. Otherwise it won't sound like effects are coming from above. This can be a problem with wall mounted solutions.
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Revel C763L is the canonical "best ceiling speaker for home theatre" as it was widely used for mastering BluRays. It's an angled speaker that sits in the ceiling, but I don't know if the angle will be correct for your setup. I also don't know if Revel makes brackets for ceiling mounting something like an M106, but something like that could work as well.