That would involve my knowing how all the knobs and dials work on here. Best for me to concentrate on reading private messages.
From here the govt can go two ways to gain the votes needed to secure a deal in parliament. The first is to pivot towards the opposition and support a customs union, that will alienate the ERG as a customs union will mean no independent trade policy. The second is further towards the PM's own party and hence towards the ERG. Looking at the news this morning, I suspect that is the PM's approach, I cannot see this strategy securing a majority in parliament, it will improve the numbers, but it won't appeal to those who dislike the backstop, we know who they are! Recall, the backstop is an EU redline not a govt redline, PM cannot change the backstop unless the EU blink first. If all the ERG rebels come onside, she will still lack the backstop haters, without them there's no majority. PS. It is not clear if a customs union has to include freedom of movement, Turkey have a customs union with EU, but not freedom of movement, important to add that Turkey's custom union is historical and may not be possible to replicate at this time. Edit: Generally, the four freedoms, including freedom of movement, are part and parcel of the Single Market, which is not the the same as a customs union.