And what if I want a big map, with twice as much height?
You won't need it, It wouldn't fit for the actual league scheme, you would need a completely new scheme, even could consider adding more worms to it. That's why I hate bigger maps than the default size for mole maps, if I had to play it often I would never accept to play my opponent with a map bigger than the default size, this confuses the timing you have pre-recorded in your mind, for example, when you reach the roof in the left and need to go all the way to the right by walking or with jump+chute to atack, I would have the average time needed for it pre-recorded in my mind for that exact map size. But if everytime I play a different map size I would feel insecure to attempt something like that. I think you got it, the bigger the map the bigger the time needed.
Remember, I'm considering league patterns, ofcourse in funners matches you can create anything you want and this method of map generate wouldn't fit for you.