I don't think you can do that directly since the admin server is different to the user server, they are two separate ExpressJS instances. The dialogue you've shown is for the the admin server I think?
I don't use Dashboard for anything complex so I can't really comment on how easy it is to secure it.
However, I do know that you have access to ExpressJS middleware with uibuilder so if you don't need the simplicity of Dashboard, you should be able to build something in uibuilder. This should get easier still with v2.