I think your concern is valid. The format of RSS is perfect for "news"; i.e. information that has date pertinence, which controls how typical RSS readers aggregate and publish the contents. People look in an RSS reader to see new, syndicated stories. I wouldn't want to subscribe to your feed and suddenly get 15,000 "stories" all at once, all marked as "unread".
If your product list is mostly unchanging, IMHO RSS isn't the right format. Instead, you might use plain old XML, in any format you choose... you might want to find a decent XML standard schema and adhere to it. Such a feed is usually called a product feed, not an RSS feed.
You might even offer your product list as CSV or a REST API.
When your product offerings change by adding or removing items, you might consider publishing THAT as RSS. Like, "Today's new products" or even "Yesterday's most popular products" - even if the stories are mind-numbing analytics data, RSS is a good way to publish stories that have a timely aspect.
And... some web services [base.google.com] do use RSS for data feeds. 'Takes different strokes, as they say.