Expose Aluminium on a Aluminium PCB

Short Version:

Can we expose the Aluminium core of a Aluminium PCB to a surface?

And if so, how? Is there a Gerber layer we can use for a (inverted) Thermal insulation mask?

Long version:

The Aluminium PCB stackup looks like this

-Aluminium Base

-Thermal insulation

-Copper

-Solder Mask

-(Silk screen)

I now want a area (around a hole, for a screw) to have exposed aluminium. There should be no silk, no solder stop, no copper and no thermal insulation. The area has a diameter of about 4.5mm around a hole with 3mm diameter.

Can you manufacture that?

And if you can, how should i name the layer that indicates where there is no Thermal insulation?