The sales folks I know are all very hard workers who often get yelled at for flaws in the software that the engineers didn't care much about. They have an overall view of the product that many engineers should but don't have. They travel a lot additionally to their actual work time which is much bigger than 20 or 30 hours. Also, I have seen engineers being as much guilty of feature creep, if not more than sales. Sales usually want the feature they need for their current customer - fair game (product management must prioritize for the greater good), and they would like the features to be implemented well. Of course their job doesn't scale that well, but they are still very important for major contracts.

Maybe if your sales team is not working this way, you should consider a new employer, the same way many are advocating when the engineering team is broken. Product management, engineering, marketing and sales should work together.