[sgtusmc]

Just my 2 cents. The rear does look really close to the floor. With towing or heavy loads it's only going to get closer. I'd cut the opening a few inches wider and build a metal plate with a 3-4 inch hump around the area. Line both the top and bottom of the hump with heat shield mat. With the thickens of the wood, I doubt you'd even be able to tell it was there. You could even hinge it for access to the rear-end.