There is issues with fire on certain trucks i have been told with EGR systems. These get that hot there can be a fire in certain applications. Some have to be fitted with special heat guards but this still is a problem. The temp's that these can get up to is very high. I would not recommend you put vents in hood for a number of reasons. One being you could be liable if any thing was to happen and the manufacture would say that these vents were not supposed to be on the truck. My suggestion would be go back to manufacture and tell them that the trucks are not suitable as they stand and need modification's