Chances are you won't get an airspace waiver YMMV, what you may get is a Wide Area Authorization that allows flights under published grid altitudes and coordination for anything over or in a 0 grid square. The paperwork looks just like a waiver.
We have a daylight waiver for class g, and two wide area authorizations for day / night operations in Class D and Class C each with their own altitude restrictions (UASFM) and coordination requirements. The daylight waiver was came first then we submitted for two airspace waivers that came back...
My Department operates 107 with waivers for daylight and two airspace authorizations for a class c and class d airport. We haven't found the need for a COA yet. Doesn't hurt to have one, but you can get Department waivers on the 107 side, they no longer have to be issued to an individual.
I agree, the only reason that we would be on the radio anyways is ATC direction or in direct comms with a pilot of police helicopter to coordinate a scene handoff.
We do the same procedure, we estimate a Minimum Safe Altitude in advance, climb to the height and do a 360 scan of the Operating Area to ensure we have clearance and then don't operate below that.