NS,
You're a cock-eyed optimist. I think it will be incredibly difficult to get a motion through approving s second referendum. EU commission saying No Deal is 'a likely scenario' and I fear that it is possibly the most likely scenario now.
Sorry - missed this before. I think you're right inasmuch as getting approval for a second referendum would be hard (though I think that's what should happen because the first one was so corrupted, and because parliament can't reach a decision of its own) but what's interesting about the permanent customs union option is that some tories who may be sympathetic are saying they can't back it because it wasn't in their manifesto and it's not what the 17m odd voted for. The second bit is bollocks of course - part of the cleverness of the wording of the referendum is that no matter which of the multiple leave options are put forward the proponent will say "and that honours the result of the referendum" as if in some way each can claim that all 17m wanted each possible model. That can't be though - some would be appalled at the idea of leaving the customs union, some would be appalled at retaining it etc.
As for the manifesto part though, maybe that's a way through - pick an option and put it back to the country for a vote on the basis that it wasn't in the manifesto so they'd need a new mandate. Perhaps if parliament skinnied down to, say, May's deal or customs union (both subject to public ratification) and voted on a winner, then the referendum would be:
Remain vs
Parliament choice exit vs
No deal exit
With first and second choice options.
If any of them got more than 50%, that'd be the winner. If none of them did though, then you'd eliminate the third place one and go with the majority cast for either of the remaining two.