Bunk End Aluminum Trim Removal

I have a 2004 Skamper camper that has a rotten bunk end. I've removed it and completely stripped it apart - except I cannot remove the extruded aluminum trim that is adhered to the 1" aluminum perimeter frame. It's like a silicone material. I've tried knives and heat to no avail. Anyone have any ideas on how I can get this removed without damaging the extrusion? A chemical? I've also removed the perimeter rivets as well.