Get some sort of heat shield installed. I'm guessing it's a muffler heating up the trunk floor? DEI makes really nice products but there are probably local suppliers of similar products closer to you.
Something like this:
www.designengineering.com
Something like this:
Floor & Tunnel Shield II™ - 10" x 10"
Use as a barrier to reflect and insulate from any heat source. Designed to provide the best possible heat protection in areas where high temperatures are always present and problematic, Floor & Tunnel Shield II limits heat transfer on fire walls, transmission tunnels, floor boards, fuel cells...
www.designengineering.com
