Schiek,
I wear a size 52 shoe and have the Sidetrak size XL booties
(see
http://www.sidetrak.com/Catalog/cooldays.html). They stretch pretty well, but the Velcro closures don't _quite_ connect without a lot of pulling and tugging on my part. Even then, they never look as smoothly sealed as the ones in the photo do. My sense (and frustration) is that they're _just barely_ too small for my feet, but I'd bet that they'd fit your size just right.
Before I stumbled upon the Sidetraks, if it was cold and wet I'd just wear an extra pair of socks and those chemical toe warmers. Having wet feet is okay with me, as long as they're not _cold_ and wet.
Let us know what you find that fits you!