I really think that the suitable provision is that there are toilets for males and others for females. Both sexes should use the ones designed for them. Third or fourth spaces will take up space, cost a fortune and be impractical in smaller premises. In airports or shopping centres they'd be fine, but in a small cafe or shop it just doesn't make sense. TW have been telling women for years that we are at no risk from men, so they can take their own advice, unless it is practical for 'trans' spaces to be installed.
Yes it will be awkward at first, but just as women had to get used to having men in our spaces, over time TW will get used to using the Gents, too.