If you load a map in your client console, turn on sv_cheats 1, use the 'noclip' command and go out of bounds, this behaviour is exactly what I want. You can see the entire map instead of a black screen. However, if you do this on a hosted server (whether you use sv_cheats 1 and noclip or just sm_noclip) the screen is black.
Strangely enough, if you do the first method I mentioned and then load into a server, you will get the desired results; but this requires having loaded at least one map in your client console first.
Is it possible to achieve this result on a server without first having to load a map in your client console?