They're heavy though - tricky to manoeuvre whilst tipped up?
Having sensible points to grip it, and somewhere to stand that doesn't foul the wheels or seat, seems to be the key to getting tadpole trikes through gaps sideways. Weight matters less if you can support it without having to bend an elbow.
We decided barakta could do it pretty well if the seat was removed, by hooking one of her fused left fingers around a chainstay to support the bulk of the weight while her right hand controlled it. Though as we've been riding together we've generally gone for the much less complicated two-person lift (which is greatly simplified if there's a lockable rear brake) to get it through our door.
Alternatively, if it's a longer passage, turn it on its side, and rest one of the wheels on a Mk 1 skateboard.
More pragmatically, the issues discussed in this thread