Hello
If the geometry of your piece and its use allow it, you might consider replacing the silicone foam with the PEEK GF material (glass fiber loaded), which can be shaped by CNC machining: it's a technical polymer with good thermal resistance capabilities, and that can be machined with high precision. You can find its characteristics on our website: https://xometry.pro/fr/materiaux/peek-charge-de-verre/
However, it is an expensive and very rigid material, therefore if you want a flexible material, you will need to search for a flexible plastic material suitable for 3D printing and/or plastic injection that can withstand temperatures above 250°, which we do not know of.