[Dominik]

I agree with iTbites. The heat transfer from the mount is your smallest problem.

I would like to see a pic of your engine bay, radiator ducting and hood to see where you can get rid of heat.

My best version was: All aluminium engine, hood cut open like a Grand Sport hood, no rubber seal to hood, no inner fenders, all air ducted through the radiator, except (this is important) I left the top open to allow air to flow into the engine compartment.

Also open louvers, and you could help evacuating the engine compartment (when driving) by adding a small (Gurney!) flap at the bottom of the foot boxed to create a suction movement.

My headers were never coated, nor wrapped, my foot boxes not insulated. I did have a heat shield between headers and brakes. Maintain a 1" gap between shield and part.

You could try to mount your fuel log away from the motor to see if it improves, for a start.