I gotta say I really like the idea....But, from my experience, anything that has any sort of texture/additive is almost impossible to roll or brush on evenly. Here's a pic of what I used on the underbody and wheelwells of my car. After two hard Wisconsin years it still looks great. The spraygun is called a "Schutz" gun and only costs about $20. It will spray some amazingly viscous materials since it basically has a straight through 3/8" bore. You adjust the thickness/texture with an air pressure regulator. It seems like it would take a lot of air to work but it really doesn't because it works best in short bursts rather than long sweeping spray patterns. Mine worked out just fine with only a 3 gal. electric copressor. The latex based Henrys product I mentioned was a very light grey/tan color and I would be willing to bet it could be easily tinted to match your existing. Another thing to ponder is weather or not you''l be able to reach all the tight areas that really need to be coated in your trunk/wheelhouse sections with a brush. Whatever you decice, always do test panels first, it wouldbe almost impossible to "go back" once your trunk/floor is coated.