The quick way to handle this with CSS would be to float both the content and the thumbnail rather than just floating the thumbnail beside the content. For instance,
.post-content { float: right; width: 560px; } /* The thumbnail's already floated, so you won't need to do anything for that. */
Note that this selector will affect all of your posts, site-wide. If you only want to do this for this specific post, you might want to wrap the content in a div with a more specific classname from within the post editor. (Though it might come in handy site-wide if in the future you have more content on the other services pages and the content then grows longer than the height of the thumbnails.)