It's not like making back wall doors is technically impossible, it only requires some work on the MCDs. I don't know if it's worth the trouble, but it's certainly possible.
It's not only the doors, there are several wall tiles and other stuff which would need a north turned version also, like UFO Navigation tiles etc...
The main poitn thou is that those would barely be visible since the view angle from the player wouldn't really change.
And regarding procedurally generated UFOs: this has already happened. Xcomutil did this. It worked as intended.
Yes i XcomUtil did this, but to implement this in OpenXcom would require changeing the Source Code itself.
Maybe someone can digg out the XcomUtil Source Code and we then can try to reproduce this behaviour as a advanced Option.
One other question is, if it could be made so that you have a pool of maps (Maps of current mod+vanilla+10 spaces) the game then selects out of this pool, so can have the vanilla maps, the turned version or new interior ones or a randomly generated one.