oil bubbles will appear in the coolant as the gasket is burnt. Of course this can take a little time.
In your case, if believe in imperfectly bleeding.
It´s useless to remove a thermostat in hot areas, even if some mechanics do it. As the thermostat is working perfect, it will open due to it´s normal regulating temperatures. As the thermostat is full open, for the cooling system it is like that, that there is no thermostat fitted.
But the working temperature of the engine will be reached much later (or never), as no thermostat is fitted.
