Unfortunately you can't currently manipulate the format in which RSS feeds render. Instead, I'd suggest you use a free service like Feedburner (http://feedburner.google.com) to optimize your feed as you see fit. All you need to do is provide Feedburner with your raw RSS feed URL, and then under "Optimize" they offer a service called "Summary", which should achieve something similar to what you've mentioned. You then embed/provide customers with the Feedburner URL as opposed to the original URL.
If you want something even more custom, consider Yahoo Pipes perhaps - it's able to completely manipulate RSS feeds and spit them back out in a variety of formats.
Hope that helps,