A simplification but pretty robust
The only benefit of any Brexit deal is they are less bad than no deal.
If you make no deal a none option you get the following:
SM+CU is pointless
SM without CU doesn't solve Irish Border & we lose existing trade deals
May's deal is not a deal, but is also a bad deal we could be locked into
No SM and no CU creates damage the country would not support
There is no other deal beyond the above because...
All other deals rely on 27 sovereign countries publicly capitulating to the UK
There is literally no #brexit that makes sense or would be acceptable
Brexits are only better or worse, more likely or less likely, than other Brexits.
No Brexit can stand on its own merit as a good Brexit
There is no majority in the UK for any given Brexit, only a majority, once, for a "pick your own #Brexit"