Mark,
Peter J insulated his old Roadster tunnel. It is doable & the thread is on here somewhere.
This is the thread......
http://www.talkmorgan.com/ubbthreads.php/ubb/showflat/Number/305029/Searchpage/1/Main/16418/Words/Dynamat/Search/true/Re:_The_Road_to_Audio_Nirvana#top
My main aim was to cut road noise, a secondary benefit was that heat soak from the engine was significantly reduced.