The only way out I can see for the UK is a 3 way referendum - No deal, May's deal, No Brexit
You are being rational. You need to close your eyes and use your imagination in order to perceive how discussions over a referendum question would go. Yes, the only logical question for a referendum (if we are forced into it) is a ranked choice between those three options. However, leavers are going to argue that such a restricted set of options is unfair. It should include other options, even if we know the EU will not accept them.
The UK staying in the EU, ironically enough, is liable to damage the EU far more than the UK crashing out. The anti-EU populists across Europe are all rumbling - Deuxit, Frexit, Grexit, Itexit - and without a solid example of what it looks like to crash out of the EU, I wouldn't like to bet on one or more of them putting the idea to their people.
The biggest damage to the EU if the UK stays is going to be the continuing anti EU mood within the UK. I predict that UKIP will become a stronger force in UK politics. Indeed, they could reach 35% support and become the ruling party. A vote to stay now could easily end up as only temporary. Insanity is often incurable.