There is no way to tell LV that it is a global, it's not - it's as you say a VI with uninitialized shift registers.
Why would you want to skip the call? One of the good things about func.globals is the fact that they are VIs; if you try to write to it and it's busy the code will wait the microseconds it takes and then access it. If you add error IO you can use data flow to ensure execution order etc. And you can add all sorts of functionality inside it, much like an object with different methods.
