180 or 190 thermostat?

The part that you're missing in the system description is that there is an active agent in the system that can force differential pressures, the water pump. Put a restriction in downstream of it and if the pump is capable of doing so that will raise the partial system pressure between the pump and the restriction. It won't raise the total system pressure, only the region between it and the restriction. Which further aids our cause by making the coolant around localized hot spots even harder to boil. From a pure science perspective it wouldn't look any different than an A/C system's pressure distribution.