In this, it may actually be a smart move for Mrs May to go all out for "all out" on the broad assumption that EU member states have very different ideas - and if we do end up "half in, half out" then Mrs May can deflect the blame and hail a "workable compromise" on single market participation.
As yet we do not know what the respective red lines of member states are or even what the Commission has in mind - or if it even has a united view. And though it is safe to assume that May is operating with only half a clue we can likely say the same of her counterparts.
This is why I'm not making any predictions. We know where it would likely go if all the parties had all the facts but each party has only half the facts and we can only guess which half they don't have. At some point Mrs May will have officials whispering in her ear telling her what she can't do and what we are not equipped to do. That's when our own red lines start to fold. Things will look very different when the pennies start to drop. What is said between now and then doesn't really matter.