I went for the A23s as they're sold as being tubeless ready, although I think that's more applicable for the 700c market, though I'm hoping the rim design is still the same. One day in the future maybe Schwalbe will come out with a tubeless ready Marathon Plus, but for now it would be nice to see if I can get away with a semi-ghetto workaround.
But yeah, without sealant it's a no-go and even then, there just isn't the familiar 'pop' when the tyre inflates, even with a compressor. I'm really hoping the autopsy points towards bad taping on my part.
(edited for poor grammar)