But this thread is about the situation where there is no local ATC operator and presumably making a let down commonly available. My point was that there would be no way of the remote radar unit coordinating with local traffic if there was no-one in the tower to phone.
An IAP is always commonly available, (unless they switch off the aids of course! which actually happened to me...) it is the clearance to actually do the IAP which seems to be the main reason why we haven't followed America / NZ / Oz / France and their GNSS / LPV approach at a large number of unmanned GA airfields.
Once established on any procedure, you change to the airfield frequency (be it A/G or A/A or ATS or whatever it may be) and you announce yourself, "G-ABCD established GNSS approach runway 03, 5 miles to run". Thereby informing "local traffic" of where you are, your intentions, and where you are going.
ATC generally only allows 1 clearance per airport at any one time, so you need to close the flightplan / call area ATC to tell them you're on the ground, and not coming back into the system so that the next plane can get a clearance to do the approach.
It works very well elsewhere - why can't it work here?