great shots. I've also joined the extension tube club, despite what I said earlier. reverse coupling ring and reverse mounts just don't work as well. Lack of aperture control is the decisive factor. Haven't got around to using them yet, but I trust these Kenko tubes with electronic contacts will be up to the job. They are not cheap!
My tube is a very old Manual Nikon tube. I can't speak for Canon but Nikon offered a reversing adapter to manually control the aperture on their old lenses. It also took a threaded filter I believe. You could try a T mount bellows and fit a manual lens with an appropriate adaptors on each end.
Epic thread revival pt2. Mine just arrived at home, and I have a reverse mount on its way (from China I assume). Any top tips? I like the idea of the home made ring, but that would mean that I'd need a extension cable for my flash, for now I think I'll just use my normal flash with a home made soft box, and see how that goes.