Bloggs. When IFR are cruising in G under survailance they just advise when they are planning to leave an altitude and request traffic. As they don't give a position report the VFR has no idea if the IFR is about to descend through the same airspace.
ICAO class G airspace is a see and avoid airspace when VMC exists and it works very satisfactorily in low traffic densities . If safety dictates that traffic needs to be given on VFR that's ICAO class D.
Put it in where required.