There are reflective faced versions of MLV that will protect it but you really want to be sure there's no guarantee it will help. It's worth thinking about since suspending a 1 lb/ft², flexible material over an engine isn't a trivial task.
For a barrier on the hood to help, noise needs pass through the hood and windshield. Most modern cars have hoods that slope forward and windshields that slope backward. The oblique angles make it unlikely that much sound will take that path into the passenger compartment. I've installed barriers on hoods and found no measurable difference.
Most engine noise enters the passenger compartment through the lower firewall and front floor. Even if the barrier on the hood makes some difference you aren't likely to hear it until you cut off the dominant entry points. I encourage people to treat the interior first and return to the hood if they need to. Very few do.