I don't really think it'll takes too much space, people will scroll no matter what, so stretching the page with some pixels is not going to hurt anybody, and it's not really annoying because I'v been on some GFX Forums, and in those forums they let us use three or four signatures, the size doesn't matter as long as it doesn't ruin the whole page by stretching it in two directions, I usually scroll down in order to see the posts and I'v never been annoyed for that, as a matter of fact, nobody has ever complained about it.
Anyway, if you still think that vertical signatures stretch the page, can you guys try to find the correct sig size that can let us use decent vertical signatures without overstretching the page?