if your set on mounting on the trunk lid, then you should think about this... Which amp runs more efficiant at your intended load. I would put the amp that is less likely to generate heat on the lid and but the others that will be a a lower impedance in an airconditioned space. If your not sealing off the trunk from the cab, then I would get some fans to channel the AC air into the trunk to help the lid mounted amp. Most likely your going to have to use thin layers of deadener to the lid, get some mounting points set up and the make sure your bottom amp vent have room to breath. After all that, you can use foan to fill in the areas that nee more deadener support. Is this a show car or something?