Can you run your website on a different port? I know that
http://stuffs:2003/stuffs looks weird, but you're probably on a dynamic IP anyway with a cable modem, so you already have a nasty URL...
Or you could see if they offer "business" cable modem service which is really just the same thing without the port blocking and give you a higher speed limitation (sometimes they also QOS your packets higher priority on the network). It's usually not too much more expensive, and you get a few static IPs to use.