Second this. I have 2 sets of Windows credentials at my job as well - one for my normal work, and elevated creds for DevOps-y stuff. I can log into the node in question directly with my elevated creds, and then run SSMS from there, but then I miss out on the LINQPad-y goodness that I have come to know and love.

Although, gotta say, I did NOT know about the Run As option. That's slick, even if it is a bit of a PITA.

SQL Authentication is not a substitution. At my job, I have three different Windows AD userid: 1) my standard network login, which gets me on the development databases, 2) a higher privileged userid (which requires requesting a temporary password) for access the production db (but cannot be used to log onto a desktop PC), and 3) a standard network login for the west coast office. To use either of the latter two, I have to launch a separate instance of LinqPad (shift-right-click, Run As...) which is a major hassle.

There is already the ability to use SQL Authentication.