If it can be of any help. In Belgium , the people who do shoe repairs have a tool on wich they put your shoe overnight or even a few days to "stretch" it a bit.
The dictionary cals it "last" . I hope I use the right word. With a screw they make this last smaller and bigger. You can even put the shoe in water for a few hours to make the leather more supple before you do it. With a "normal" shoe , you put water in the shoe, but with the gore-tex membrane , it might not help.