It's a perfectly reasonable approach. People confuse sitemaps with the idea of presenting Google with a complete 'view' of your site that they will follow. In fact, sitemaps are just a way of adding on data to the usual crawl process. So it doesn't matter whether you have a 'positive' or 'negative' reason to submit.
The other method would be to create a page with links, as you suggest. if you do so, I would recommending using the "submit to index" feature in GWT. But to be honest, creating something with enough equity to get speedy crawling of thousands of URLs would not be a good idea IMO.