Your best option here is to switch to Windows Authentication. You can do this by running the "Server Tools" app (you'll need to remote desktop to the Deployment Manager server to run it). When using Windows Authentication on an intranet site, most web browsers will auto-login by default, but if they don't, then you can always enable it.
For security reasons, we don't support auto-login using Deployment Manager authentication. Section 3, "LOGIN CSRF" of this research paper details the kind of things that can go wrong if we did: http://seclab.stanford.edu/websec/csrf/csrf.pdf
Also, for security reasons, we don't have a guest account and don't recommend one. Giving each user their own account makes it much better to both audit changes, as well as lock read access down.